How to make a limit on the use of any function in the free version of the application?

Question

Android

I want to make a limited free version of the application with the ability to upgrade to a full one. I have a function that I want to limit the use of for a user, for example, 100 calls per day. It is clear that the counter. And how to store it properly so that it is not immediately hacked?

Answer 1

Place this counter on the server.

Answer 2

the most correct thing is to store it on the server, but it can be in sharedpreferences ... yes, when the application is deleted, the counter will fly off, but if the user needs your application so much that he agrees to demolish it and install it several times a day, rejoice) these are potential buyers, let your application be better / put than a competitor