If you upgrade directly inside the app, the payment is handled by your device's store. These stores usually support:
Apple App Store: Credit/debit cards linked to your Apple ID, Apple Pay, and App Store Gift Cards. See Payment methods that you can use with your Apple Account
Google Play Store: Credit/debit cards, Google Pay, mobile phone billing (with supported carriers), and Google Play Balance/Gift Cards. See Accepted payment methods on Google Play
Note: If your payment is declined, please ensure your card is authorized for international transactions or contact your bank for more details.