In my application are 10 free levels, everyone can play them without doing in-app purchases. But if you want more levels, then you need to buy once a non-consumable product in the application. After you purchased it, you will have access to all levels that are currently available and to all levels that will be released during the next weeks.
But how can I know if someone bought the non-consumable product? Is it necessary to send at every reboot of the application a request to the Apple App Store to check if the current Apple ID has bought the product?