Accepted payment methods on App Store
To make purchases from the App Store you need an Apple ID and a valid payment method. See what forms of payment are accepted in your country or region: https://support.apple.com/en-us/HT202631
If you can't make purchases, you need to update your payment method or add a new one: https://support.apple.com/en-us/HT201266
If you already verified that a payment method is available in your country or region and you're still having trouble, contact your financial institution.
Accepted payment methods on Google Play
You can make purchases on Google Play using payment methods from your Google Account. Available payment methods vary by country: https://support.google.com/googleplay/answer/2651410
Here's how to add, edit, or remove payment methods you use for Google Play purchases: https://support.google.com/googleplay/answer/4646404