Subscribing app in app store for 3 months

I want to give access of my app to user for just 3 months. I user want to continue开发者_JAVA百科 with the app he should pay again for the same.

Can anyone suggest me how can I Do the same.

Thanks in advance Gurpreet

The obvious mechanism would be in-app purchase with StoreKit. It can be used for subscriptions :

Subscriptions provide access to content or services on an extended basis. For example, your application might offer monthly access to financial information or to an online game portal. You should define a reasonable renewal frequency to avoid bothering users with unwelcome reminders. Be aware that you are responsible for both tracking subscription expirations and renewal billing; the App Store does not monitor subscription duration and does not offer an automatic billing mechanism.

http://developer.apple.com/iphone/library/documentation/NetworkingInternet/Conceptual/StoreKitGuide/Overview%20of%20the%20Store%20Kit%20API/OverviewoftheStoreKitAPI.html