I have an app that needs user log-in and when the user do a succesful purchase I save that the purchse and the user, so everytime that the user logs in the app I check in my server if that user has purchases and If he has purchases I restore his purchases.Do I need a restore button?, Do I need execute the function restoreCompletedTransactions() ?
If I restore muy purchases with my server, Do I need the restore button?
You do not need to implement restoreCompletedTransactions if you have an effective method to restore IAPs to new devices and devices that have deleted and then reinstalled the app.
An app that requires logging into some account in order to function will not pass review. Apps must do something without requiring log-in or any other personal information.