title: In App Purchase: Detecting whether a feature has already been purchased in another device
body: <p>Apple demands that the features sold on In App Purchase are available for all the devices of the user. Currently, my app asks the NSUserDefaults singleton if the feature is available, when the user bought the feature from the same device it works great, the problem is that the other devices the user may have are not aware of this purchase until they repeat the purchase process and the store tell them so.</p>
  
  <p>So I was wondering if this is OK. If not, what should I implement to detect this information?</p>