You can purchase the Premium subscription at any time. To do so, tap the gift icon located to the right of your game balance (see the attached screenshot). Then, tap the Premium Subscription banner, which is the first option in the game bank.
There are currently three types of Premium subscriptions available:
- Weekly subscription
- Monthly subscription
- Quarterly subscription
Simply select the subscription type you prefer and proceed with the payment. Please note that all transactions are processed through the App Store or Google Play Store.