title: How to keep track of the purchased items in StoreKit?
body: <p>I have implemented an in-app purchase in my app that allows the user to use an advanced feature once (consumable product). How is it possible to track if the user have used this feature or not after the payment ?</p>
  <p><strong>Example:</strong></p>
  <p>The user have done the payment and suddently killed the app, he should be able to use the advanced feature after relaunching the app.</p>
  <p>I do not want to use <code>UserDefaults</code> to track this. Does <code>StoreKit</code> provide any solution to that ?</p>