in app purchaes

Hi, I'm using iStore in my app for users to make membership purchases; however, the app has been rejected by apple for the following reason: "We noticed that your app includes, or accesses paid digital content, services, or functionality by means other than in-app purchase, which is not...

Hello everyone, Does anyone know how to validate or check when promo code has been used for a specific app, I have an app with Monthly and Yearly Subscriptions and i have generated a few promo codes for some people to try out the app and advertise it for me, the problem i'm having is that...