This seems like a major oversight and it’s weird that Unreal offers IAP functionality at all without this important feature.
If it’s impossible to check whether or not a user already purchased an IAP, then it’s impossible to carry over his purchases if he installs the app on other devices. Or just resets his device.
@Arturogalaxy It would be very helpful if you could provide the modified version of your GooglePlayStoreHelper.java instead of screenshots. This way it will be easier to understand what you did and easier to add it to our own GooglePlayStoreHelper.java using Diff.