Welcome gift in app

Hi everyone, I tried searching but couldn’t find any topics, I apologize if this has already been covered.

My problem is as follows: when the user installs the app, he gets some free credits to use it. Once the credits are used up he will have to purchase them. Clearly the problem is if you uninstall and reinstall the app.

  • Is there a method to save data permanently on the phone so that it is not deleted when the user uninstalls the app? can it create serious problems in terms of permissions?

  • I could have the user log in via firebase authentication, although I would like to avoid collecting emails. If so, does firebase authenticator still work correctly with api 33 or 34?

  • are there other methods?

Thank you!

Use an in app billing extension
Taifun

ask the user to log in. if the user have an account already ,get his credits from firebase
if he is new to the app ask user to signup and give him credits store credits number in firebase and deduct when needed