Is this use case for in-app billing possible?

Question

Android

Hello. I'm going to develop an application that will take content from a third-party server (I only have access to it using the API) and provide it to users through a subscription. The question is, is it possible to safely organize the provision of a subscription and checking users for its presence in the application itself without using a server on which such checks would take place, or without it, absolutely nowhere?

Answer 1

Everything critical can be reliably checked ONLY on the server. No validation on the server - can be hacked. There are no other options