feat: tariff switch direction control, fix device pricing within tariff limit

Tariff switch direction:
- Add TARIFF_SWITCH_UPGRADE_ENABLED and TARIFF_SWITCH_DOWNGRADE_ENABLED
  settings to control allowed switch directions
- Guard all 10 entry points: instant switch (list, preview, confirm),
  legacy switch (list, select, confirm, daily confirm), cabinet (preview,
  execute), purchase-options API
- Filter tariff lists by allowed direction, show "unavailable" when
  both directions disabled
- Expose settings in cabinet purchase-options response for frontend

Device pricing fix:
- Devices within tariff.device_limit are now free when restoring
  (was charging for all devices regardless of tariff inclusion)
- Fix max(100, price) minimum enforcing 1 RUB even when
  chargeable_devices is 0
- Apply fix across all endpoints: bot handlers (confirm_change,
  execute_change, confirm_add), cabinet API (legacy purchase,
  modern purchase, get-price, save-cart), inline keyboard display

.env.example

@@ -254,6 +254,15 @@ WEBHOOK_NOTIFY_DEVICES=true
 #   - Подходит для продажи готовых пакетов услуг
 SALES_MODE=tariffs
 
+# Управление сменой тарифа (для SALES_MODE=tariffs)
+# UPGRADE / DOWNGRADE:
+#   true  / true  = все направления разрешены
+#   true  / false = только повышение (на более дорогой тариф)
+#   false / true  = только понижение (на более дешёвый тариф)
+#   false / false = смена тарифа полностью отключена
+TARIFF_SWITCH_UPGRADE_ENABLED=true
+TARIFF_SWITCH_DOWNGRADE_ENABLED=true
+
 # ===== ТРИАЛ ПОДПИСКА =====
 TRIAL_DURATION_DAYS=3
 TRIAL_TRAFFIC_LIMIT_GB=10

app/cabinet/routes/subscription_modules/devices.py

@@ -108,7 +108,24 @@ async def purchase_devices_legacy(
             detail='Докупка устройств недоступна',
         )
 
-    base_total_price = device_price * request.devices
+    # Устройства в пределах тарифного лимита — бесплатные
+    current_devices = subscription.device_limit or 1
+    if tariff:
+        tariff_included = tariff.device_limit or 0
+        if current_devices < tariff_included:
+            free_devices = tariff_included - current_devices
+            chargeable_devices = max(0, request.devices - free_devices)
+        else:
+            chargeable_devices = request.devices
+    else:
+        free_baseline = settings.DEFAULT_DEVICE_LIMIT
+        if current_devices < free_baseline:
+            free_devices = free_baseline - current_devices
+            chargeable_devices = max(0, request.devices - free_devices)
+        else:
+            chargeable_devices = request.devices
+
+    base_total_price = device_price * chargeable_devices
 
     # Lock user row to prevent TOCTOU on promo-offer state
     from app.database.crud.user import lock_user_for_pricing
@@ -366,10 +383,27 @@ async def purchase_devices(
         days_left = max(1, (end_date - now).days)
         total_days = 30  # Base period for device price calculation
 
+        # Устройства в пределах тарифного лимита — бесплатные
+        if tariff:
+            tariff_included = tariff.device_limit or 0
+            if current_devices < tariff_included:
+                free_devices = tariff_included - current_devices
+                chargeable_devices = max(0, request.devices - free_devices)
+            else:
+                chargeable_devices = request.devices
+        else:
+            free_baseline = settings.DEFAULT_DEVICE_LIMIT
+            if current_devices < free_baseline:
+                free_devices = free_baseline - current_devices
+                chargeable_devices = max(0, request.devices - free_devices)
+            else:
+                chargeable_devices = request.devices
+
         # Calculate base price before discount
-        base_price_per_month = device_price * request.devices
+        base_price_per_month = device_price * chargeable_devices
         base_price_prorated = int(base_price_per_month * days_left / total_days)
-        base_price_prorated = max(100, base_price_prorated)  # Minimum 1 ruble
+        if chargeable_devices > 0:
+            base_price_prorated = max(100, base_price_prorated)  # Minimum 1 ruble
 
         # Lock user BEFORE discount computation to prevent TOCTOU on promo group
         from app.database.crud.user import lock_user_for_pricing
@@ -627,8 +661,25 @@ async def save_devices_cart(
     days_left = max(1, (end_date - now).days)
     total_days = 30
 
-    base_total_price = int(device_price * request.devices * days_left / total_days)
-    base_total_price = max(100, base_total_price)  # Minimum 1 ruble
+    # Устройства в пределах тарифного лимита — бесплатные
+    if tariff:
+        tariff_included = tariff.device_limit or 0
+        if current_devices < tariff_included:
+            free_devices = tariff_included - current_devices
+            chargeable_devices = max(0, request.devices - free_devices)
+        else:
+            chargeable_devices = request.devices
+    else:
+        free_baseline = settings.DEFAULT_DEVICE_LIMIT
+        if current_devices < free_baseline:
+            free_devices = free_baseline - current_devices
+            chargeable_devices = max(0, request.devices - free_devices)
+        else:
+            chargeable_devices = request.devices
+
+    base_total_price = int(device_price * chargeable_devices * days_left / total_days)
+    if chargeable_devices > 0:
+        base_total_price = max(100, base_total_price)  # Minimum 1 ruble
 
     # Apply discount from promo group
     period_hint_days = days_left
@@ -724,9 +775,26 @@ async def get_device_price(
     days_left = max(1, (end_date - now).days)
     total_days = 30
 
+    # Устройства в пределах тарифного лимита — бесплатные
+    if tariff:
+        tariff_included = tariff.device_limit or 0
+        if current_devices < tariff_included:
+            free_devices = tariff_included - current_devices
+            chargeable_devices = max(0, devices - free_devices)
+        else:
+            chargeable_devices = devices
+    else:
+        free_baseline = settings.DEFAULT_DEVICE_LIMIT
+        if current_devices < free_baseline:
+            free_devices = free_baseline - current_devices
+            chargeable_devices = max(0, devices - free_devices)
+        else:
+            chargeable_devices = devices
+
     # Calculate base price before discount (total first, then floor)
-    base_total_price = int(device_price * devices * days_left / total_days)
-    base_total_price = max(100, base_total_price)
+    base_total_price = int(device_price * chargeable_devices * days_left / total_days)
+    if chargeable_devices > 0:
+        base_total_price = max(100, base_total_price)
 
     # Apply discount from promo group
     period_hint_days = days_left

app/cabinet/routes/subscription_modules/purchase.py

@@ -353,6 +353,9 @@ async def get_purchase_options(
                 'all_tariffs_purchased': len(purchased_tariff_ids) >= len(tariffs)
                 if settings.is_multi_tariff_enabled()
                 else False,
+                # Направления смены тарифа
+                'tariff_switch_upgrade_enabled': settings.TARIFF_SWITCH_UPGRADE_ENABLED,
+                'tariff_switch_downgrade_enabled': settings.TARIFF_SWITCH_DOWNGRADE_ENABLED,
             }
 
         # Classic mode - return periods

app/cabinet/routes/subscription_modules/tariff_switch.py

@@ -119,6 +119,18 @@ async def preview_tariff_switch(
     )
     upgrade_cost = switch_result.upgrade_cost
     is_upgrade = switch_result.is_upgrade
+
+    # Проверяем разрешение на смену в данном направлении
+    if is_upgrade and not settings.TARIFF_SWITCH_UPGRADE_ENABLED:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail='Повышение тарифа недоступно',
+        )
+    if not is_upgrade and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail='Понижение тарифа недоступно',
+        )
     base_upgrade_cost = switch_result.raw_cost
     discount_value = switch_result.discount_value
     period_discount_percent = switch_result.effective_discount_pct
@@ -263,11 +275,24 @@ async def switch_tariff(
         user=user,
     )
     upgrade_cost = switch_result.upgrade_cost
+    is_upgrade = switch_result.is_upgrade
     base_upgrade_cost = switch_result.raw_cost
     discount_value = switch_result.discount_value
     period_discount_percent = switch_result.effective_discount_pct
     new_period_days = switch_result.new_period_days
 
+    # Проверяем разрешение на смену в данном направлении
+    if is_upgrade and not settings.TARIFF_SWITCH_UPGRADE_ENABLED:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail='Повышение тарифа недоступно',
+        )
+    if not is_upgrade and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail='Понижение тарифа недоступно',
+        )
+
     # Validate daily price for switching TO daily
     new_is_daily = getattr(new_tariff, 'is_daily', False)
     current_is_daily = getattr(current_tariff, 'is_daily', False) if current_tariff else False

app/config.py

@@ -148,6 +148,8 @@ class Settings(BaseSettings):
     DEFAULT_TRAFFIC_RESET_STRATEGY: str = 'MONTH'
     RESET_TRAFFIC_ON_PAYMENT: bool = False
     RESET_TRAFFIC_ON_TARIFF_SWITCH: bool = True
+    TARIFF_SWITCH_UPGRADE_ENABLED: bool = True
+    TARIFF_SWITCH_DOWNGRADE_ENABLED: bool = True
     MAX_DEVICES_LIMIT: int = 20
 
     TRIAL_WARNING_HOURS: int = 2

app/handlers/subscription/devices.py

@@ -325,9 +325,14 @@ async def confirm_change_devices(
     if devices_difference > 0:
         additional_devices = devices_difference
 
-        # Для тарифов - все устройства платные (нет бесплатного лимита)
+        # Устройства в пределах тарифного лимита — бесплатные
         if tariff:
-            chargeable_devices = additional_devices
+            tariff_included = tariff.device_limit or 0
+            if current_devices < tariff_included:
+                free_devices = tariff_included - current_devices
+                chargeable_devices = max(0, additional_devices - free_devices)
+            else:
+                chargeable_devices = additional_devices
         elif current_devices < settings.DEFAULT_DEVICE_LIMIT:
             free_devices = settings.DEFAULT_DEVICE_LIMIT - current_devices
             chargeable_devices = max(0, additional_devices - free_devices)
@@ -352,7 +357,8 @@ async def confirm_change_devices(
         )
         # Цена = месячная_цена * days_left / 30
         price = int(discounted_per_month * days_left / 30)
-        price = max(100, price)  # Минимум 1 рубль
+        if chargeable_devices > 0:
+            price = max(100, price)  # Минимум 1 рубль (только для платных устройств)
         total_discount = int(discount_per_month * days_left / 30)
         period_label = f'{days_left} дн.' if days_left > 1 else '1 день'
 
@@ -553,7 +559,12 @@ async def execute_change_devices(
     devices_difference = new_devices_count - current_devices
     if devices_difference > 0:
         if tariff:
-            chargeable_devices = devices_difference
+            tariff_included = tariff.device_limit or 0
+            if current_devices < tariff_included:
+                free_devices = tariff_included - current_devices
+                chargeable_devices = max(0, devices_difference - free_devices)
+            else:
+                chargeable_devices = devices_difference
         elif current_devices < settings.DEFAULT_DEVICE_LIMIT:
             free_devices = settings.DEFAULT_DEVICE_LIMIT - current_devices
             chargeable_devices = max(0, devices_difference - free_devices)
@@ -572,7 +583,8 @@ async def execute_change_devices(
             devices_discount_percent,
         )
         price = int(discounted_per_month * days_left / 30)
-        price = max(100, price)
+        if chargeable_devices > 0:
+            price = max(100, price)
     else:
         price = 0
 
@@ -1215,7 +1227,22 @@ async def confirm_add_devices(callback: types.CallbackQuery, db_user: User, db:
         )
         return
 
-    devices_price_per_month = devices_count * price_per_device
+    # Устройства в пределах тарифного лимита — бесплатные
+    current_devices = subscription.device_limit or 1
+    if tariff:
+        tariff_included = tariff.device_limit or 0
+        if current_devices < tariff_included:
+            free_devices = tariff_included - current_devices
+            chargeable_devices = max(0, devices_count - free_devices)
+        else:
+            chargeable_devices = devices_count
+    elif current_devices < settings.DEFAULT_DEVICE_LIMIT:
+        free_devices = settings.DEFAULT_DEVICE_LIMIT - current_devices
+        chargeable_devices = max(0, devices_count - free_devices)
+    else:
+        chargeable_devices = devices_count
+
+    devices_price_per_month = chargeable_devices * price_per_device
 
     # TOCTOU: lock user row before reading promo/discount state
     db_user = await lock_user_for_pricing(db, db_user.id)
@@ -1240,7 +1267,8 @@ async def confirm_add_devices(callback: types.CallbackQuery, db_user: User, db:
         )
         # Цена = месячная_цена * days_left / 30
         price = int(discounted_per_month * days_left / 30)
-        price = max(100, price)  # Минимум 1 рубль
+        if chargeable_devices > 0:
+            price = max(100, price)  # Минимум 1 рубль (только для платных устройств)
         total_discount = int(discount_per_month * days_left / 30)
         period_label = f'{days_left} дн.' if days_left > 1 else '1 день'
     else:
@@ -1260,7 +1288,8 @@ async def confirm_add_devices(callback: types.CallbackQuery, db_user: User, db:
         )
         # Цена = месячная_цена * days_left / 30
         price = int(discounted_per_month * days_left / 30)
-        price = max(100, price)  # Минимум 1 рубль
+        if chargeable_devices > 0:
+            price = max(100, price)  # Минимум 1 рубль (только для платных устройств)
         total_discount = int(discount_per_month * days_left / 30)
         period_label = f'{days_left} дн.' if days_left > 1 else '1 день'
 

app/handlers/subscription/tariff_purchase.py

@@ -2666,6 +2666,18 @@ async def show_tariff_switch_list(
 
     current_tariff_id = subscription.tariff_id
 
+    # Проверяем, разрешена ли смена тарифа хотя бы в одном направлении
+    if not settings.TARIFF_SWITCH_UPGRADE_ENABLED and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+        await callback.message.edit_text(
+            '🚫 <b>Смена тарифа недоступна</b>\n\nАдминистратор отключил возможность смены тарифа.',
+            reply_markup=InlineKeyboardMarkup(
+                inline_keyboard=[[InlineKeyboardButton(text=texts.BACK, callback_data='menu_subscription')]]
+            ),
+            parse_mode='HTML',
+        )
+        await callback.answer()
+        return
+
     # Получаем доступные тарифы
     promo_group_id = getattr(db_user, 'promo_group_id', None)
     tariffs = await get_tariffs_for_user(db, promo_group_id)
@@ -2678,6 +2690,14 @@ async def show_tariff_switch_list(
     else:
         available_tariffs = [t for t in tariffs if t.id != current_tariff_id]
 
+    # Фильтруем по разрешённым направлениям (upgrade/downgrade)
+    current_tariff = await get_tariff_by_id(db, current_tariff_id) if current_tariff_id else None
+    if current_tariff:
+        remaining_days = max(0, (subscription.end_date - datetime.now(UTC)).days) if subscription.end_date else 0
+        available_tariffs = _filter_tariffs_by_switch_direction(
+            available_tariffs, current_tariff, remaining_days, db_user
+        )
+
     if not available_tariffs:
         await callback.message.edit_text(
             '😔 <b>Нет доступных тарифов для переключения</b>\n\nВы уже используете единственный доступный тариф.',
@@ -2739,6 +2759,24 @@ async def select_tariff_switch(
         await callback.answer('Тариф недоступен', show_alert=True)
         return
 
+    # Проверяем разрешение на смену в данном направлении
+    current_subscription_sw, _sw_sub_id_check = await _resolve_subscription(callback, db_user, db, state)
+    if current_subscription_sw and current_subscription_sw.tariff_id:
+        cur_tariff_sw = await get_tariff_by_id(db, current_subscription_sw.tariff_id)
+        if cur_tariff_sw:
+            rem_days = (
+                max(0, (current_subscription_sw.end_date - datetime.now(UTC)).days)
+                if current_subscription_sw.end_date
+                else 0
+            )
+            _, is_up = _calculate_instant_switch_cost(cur_tariff_sw, tariff, rem_days, db_user)
+            if is_up and not settings.TARIFF_SWITCH_UPGRADE_ENABLED:
+                await callback.answer('Повышение тарифа недоступно', show_alert=True)
+                return
+            if not is_up and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+                await callback.answer('Понижение тарифа недоступно', show_alert=True)
+                return
+
     traffic = format_traffic(tariff.traffic_limit_gb)
 
     # Проверяем, суточный ли это тариф
@@ -2960,6 +2998,19 @@ async def confirm_tariff_switch(
         await callback.answer('У вас нет активной подписки', show_alert=True)
         return
 
+    # Проверяем разрешение на смену в данном направлении
+    if subscription.tariff_id and subscription.tariff_id != tariff_id:
+        cur_tariff_obj = await get_tariff_by_id(db, subscription.tariff_id)
+        if cur_tariff_obj:
+            rem_days = max(0, (subscription.end_date - datetime.now(UTC)).days) if subscription.end_date else 0
+            _, is_up = _calculate_instant_switch_cost(cur_tariff_obj, tariff, rem_days, db_user)
+            if is_up and not settings.TARIFF_SWITCH_UPGRADE_ENABLED:
+                await callback.answer('Повышение тарифа недоступно', show_alert=True)
+                return
+            if not is_up and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+                await callback.answer('Понижение тарифа недоступно', show_alert=True)
+                return
+
     # Calculate price via PricingEngine (handles per-category discounts + extra devices)
     from app.services.pricing_engine import pricing_engine
 
@@ -3212,6 +3263,19 @@ async def confirm_daily_tariff_switch(
         await callback.answer('У вас нет активной подписки', show_alert=True)
         return
 
+    # Проверяем разрешение на смену в данном направлении
+    if subscription.tariff_id and subscription.tariff_id != tariff_id:
+        cur_tariff_daily = await get_tariff_by_id(db, subscription.tariff_id)
+        if cur_tariff_daily:
+            rem_days = max(0, (subscription.end_date - datetime.now(UTC)).days) if subscription.end_date else 0
+            _, is_up = _calculate_instant_switch_cost(cur_tariff_daily, tariff, rem_days, db_user)
+            if is_up and not settings.TARIFF_SWITCH_UPGRADE_ENABLED:
+                await callback.answer('Повышение тарифа недоступно', show_alert=True)
+                return
+            if not is_up and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+                await callback.answer('Понижение тарифа недоступно', show_alert=True)
+                return
+
     texts = get_texts(db_user.language)
 
     try:
@@ -3443,6 +3507,30 @@ def _calculate_instant_switch_cost(
     return result.upgrade_cost, result.is_upgrade
 
 
+def _filter_tariffs_by_switch_direction(
+    tariffs: list[Tariff],
+    current_tariff: Tariff,
+    remaining_days: int,
+    db_user: User | None = None,
+) -> list[Tariff]:
+    """Фильтрует тарифы по разрешённым направлениям смены (upgrade/downgrade)."""
+    upgrade_ok = settings.TARIFF_SWITCH_UPGRADE_ENABLED
+    downgrade_ok = settings.TARIFF_SWITCH_DOWNGRADE_ENABLED
+
+    if upgrade_ok and downgrade_ok:
+        return tariffs
+
+    filtered = []
+    for tariff in tariffs:
+        if tariff.id == current_tariff.id:
+            filtered.append(tariff)
+            continue
+        _, is_upgrade = _calculate_instant_switch_cost(current_tariff, tariff, remaining_days, db_user)
+        if (is_upgrade and upgrade_ok) or (not is_upgrade and downgrade_ok):
+            filtered.append(tariff)
+    return filtered
+
+
 def format_instant_switch_list_text(
     tariffs: list[Tariff],
     current_tariff: Tariff,
@@ -3450,16 +3538,21 @@ def format_instant_switch_list_text(
     db_user: User | None = None,
 ) -> str:
     """Форматирует текст со списком тарифов для мгновенного переключения."""
+    upgrade_ok = settings.TARIFF_SWITCH_UPGRADE_ENABLED
+    downgrade_ok = settings.TARIFF_SWITCH_DOWNGRADE_ENABLED
+
     lines = [
         '📦 <b>Мгновенная смена тарифа</b>',
         f'📌 Текущий: <b>{html.escape(current_tariff.name)}</b>',
         f'⏰ Осталось: <b>{remaining_days} дн.</b>',
         '',
         '💡 При переключении остаток дней сохраняется.',
-        '⬆️ Повышение тарифа = доплата за разницу',
-        '⬇️ Понижение = бесплатно',
-        '',
     ]
+    if upgrade_ok:
+        lines.append('⬆️ Повышение тарифа = доплата за разницу')
+    if downgrade_ok:
+        lines.append('⬇️ Понижение = бесплатно')
+    lines.append('')
 
     for tariff in tariffs:
         if tariff.id == current_tariff.id:
@@ -3591,6 +3684,18 @@ async def show_instant_switch_list(
         await callback.answer()
         return
 
+    # Проверяем, разрешена ли смена тарифа хотя бы в одном направлении
+    if not settings.TARIFF_SWITCH_UPGRADE_ENABLED and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+        await callback.message.edit_text(
+            '🚫 <b>Смена тарифа недоступна</b>\n\nАдминистратор отключил возможность смены тарифа.',
+            reply_markup=InlineKeyboardMarkup(
+                inline_keyboard=[[InlineKeyboardButton(text=texts.BACK, callback_data='menu_subscription')]]
+            ),
+            parse_mode='HTML',
+        )
+        await callback.answer()
+        return
+
     # Получаем доступные тарифы
     promo_group_id = getattr(db_user, 'promo_group_id', None)
     tariffs = await get_tariffs_for_user(db, promo_group_id)
@@ -3603,6 +3708,9 @@ async def show_instant_switch_list(
     else:
         available_tariffs = [t for t in tariffs if t.id != current_tariff.id]
 
+    # Фильтруем по разрешённым направлениям (upgrade/downgrade)
+    available_tariffs = _filter_tariffs_by_switch_direction(available_tariffs, current_tariff, remaining_days, db_user)
+
     if not available_tariffs:
         await callback.message.edit_text(
             '😔 <b>Нет доступных тарифов для переключения</b>\n\nВы уже используете единственный доступный тариф.',
@@ -3672,6 +3780,14 @@ async def preview_instant_switch(
     # Рассчитываем стоимость переключения
     upgrade_cost, is_upgrade = _calculate_instant_switch_cost(current_tariff, new_tariff, remaining_days, db_user)
 
+    # Проверяем разрешение на смену в данном направлении
+    if is_upgrade and not settings.TARIFF_SWITCH_UPGRADE_ENABLED:
+        await callback.answer('Повышение тарифа недоступно', show_alert=True)
+        return
+    if not is_upgrade and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+        await callback.answer('Понижение тарифа недоступно', show_alert=True)
+        return
+
     # Проверяем баланс
     user_balance = db_user.balance_kopeks or 0
 
@@ -3846,6 +3962,14 @@ async def confirm_instant_switch(
     is_upgrade = switch_result.is_upgrade
     consume_promo = switch_result.offer_discount_pct > 0
 
+    # Проверяем разрешение на смену в данном направлении
+    if is_upgrade and not settings.TARIFF_SWITCH_UPGRADE_ENABLED:
+        await callback.answer('Повышение тарифа недоступно', show_alert=True)
+        return
+    if not is_upgrade and not settings.TARIFF_SWITCH_DOWNGRADE_ENABLED:
+        await callback.answer('Понижение тарифа недоступно', show_alert=True)
+        return
+
     # Проверяем баланс если это upgrade (use locked user's fresh balance)
     user_balance = db_user.balance_kopeks or 0
     if is_upgrade and user_balance < upgrade_cost:

app/keyboards/inline.py

@@ -2310,8 +2310,8 @@ def get_change_devices_keyboard(
     tariff_device_price = getattr(tariff, 'device_price_kopeks', None) if tariff else None
     if tariff and tariff_device_price:
         device_price_per_month = tariff_device_price
-        # Для тарифов все устройства платные (нет бесплатного лимита)
-        default_device_limit = 0
+        # Устройства в пределах тарифного лимита — бесплатные
+        default_device_limit = tariff.device_limit if tariff else 0
     else:
         device_price_per_month = settings.PRICE_PER_DEVICE
         default_device_limit = settings.DEFAULT_DEVICE_LIMIT