I just recently upgraded to a new iPhone. I had a game app on my previous iPhone that I paid for (within the app to get rid of ads). However, when I went to setup my new iPhone as, well, a new iPhone, I downloaded the app again manually, but it downloads the free version and asks me to pay within the app a second time to get rid of ads again.
Everything that I search for online says that I shouldn't have to pay again.
So, how do I make it so that it knows that I've already paid?