Thank you @Claude31 for your general explanation; it proved to be useful. Regarding your final point: do you mean that transactions specifically should use In App Purchase? After reading the App Store Review Guidelines and specifically 3.1.3(d), I was actually planning to integrate an external payment service provider, given the 1 : 1 nature of our person-to-person services. Do you have experience to suggest that this would be rejected by the app store?