How do I put IAP for Unlocked Mode?

Hi guys. I wanna help to put a system on my game in Construct 3. I have a memory game, and it has 20 phases; I want a system to put just 3 phases for free and a IAP for unlocked all by paying. My game is on Google Play. I now somethings, like the ID and create the IAP on Play Console, but I can't put the logic on the C3.

After the player has purchased the product, you must remove the lock from the new levels so that the player can continue playing and save it to local storage.

The next time the player opens the game, you check local storage and remove the lock if necessary.

This means that you need to have a global variable in the code that is responsible for the status of this lock.