I'm trying to figure out how to verify that the user purchased my app before allowing them to register an account on my server. I failed with my web search - all I found was references to in-app purchase.. Is there some kind of receipt on the phone? Is it safe to send to my server etc..
EDIT - You can't query Apple for information on the users who have purchased the app? An email? anything??
EDIT2 -
Heres the deal, you can use the app all you want. But theres an optional ability to work with my server. This is expensive, if pirates start using my server I can't handle it. So I need to be able to authorize the user at my server. I'm guessing in app payment is what I'll have to use as that allows me to verify a purchase against a user/password on my site, I just didn't want the user to have to go through the hassle of the in-app payment and allow them to purchase the app upfront.