How do I update my in-app-purchase app

I have the app in apple store with in app purchase. Now I need to update the app with some improvements. I have a question about the customers who already purchased the full feature from in app purchase and how do they g开发者_StackOverflowet the new updates? I am new to in app purchase. Thanks for your help and answer!

Emmy

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If a user already bought one of the in-app purchase products, those products will still be downloaded after the user updates to the latest version of the app.

If a user un-installs or installs on a new device, the products they purchased in the past can be re-downloaded without having to re-purchase.

I'd suggest using a service like Urban Airship to make the in-app purchase process simple. They've got a great SDK for IAP.