[farhanpatel]

This is also another reason why developers choose to go the freemium route.

With apps that have their own backend its trivial to verify receipts with your server. It's hard(impossible?) to verify actual purchases with your server but In App purchases can easily be verified.

[lucian1900]

Afaik there is no way to verify purchases (since Apple never sends you a receipt for it).

It's trivial to verify in-app purchase receipts server-side, however. And that could be used to allow (or not) access to the multiplayer bits.