If a player purchases a Non Consumable item in my game, will they be able to do so again after restarting the app?

Sorry, I don’t know how to figure this out without having to spend money just to test it. Is this something Google Play does automatically, or do I need to build some kind of protection against purchasing something you’ve already bought?

You could do something in the Player Prefs for example, like “HasBoughtItem_1”, and if it’s true, don’t display the purchase again.or you can pull the purchases and go from there.

There are a number of different ways to achieve this, but with anything in programming, nothing happens automagically.