TextApp subscriptions are handled through your Apple ID billing method.
Here's what that means:
When you purchase a TextApp subscription within the app, the payment will be charged to the payment method associated with your Apple ID. This could be a credit card, debit card, or any other valid payment method linked to your Apple ID.
TextApp itself doesn't handle payments directly. The entire purchase process is managed by the App Store.
Important to Note:
TextApp currently only offers subscriptions through the App Store.