title: In App Purchase Subscription Auto Renewal
body: <p>I have implemented a couple of months ago the in app auto renewable subscription on two of my apps. I stored the old receipts of my users and contacted Apple from my server at the end of the subscription period to check if the subscription is still active.
  I noticed that some of my users are being auto-renewed form the client code itself.
  My app upon entry calls [<code>[SKPaymentQueue defaultQueue] addTransactionObserver:myObserver]</code> and when either <code>SKPaymentTransactionStatePurchased</code> or <code>SKPaymentTransactionStateRestored</code> is returned it calls my server to verify the receipt and give my users the subscription.</p>
  
  <p>I have been trying for quite some time to understand the logic behind the transaction notification the client gets at the end of the renewal period. Does anyone knows why only some of the users get the notifications and the rest require the server to revalidate their receipts? I tried to think maybe it has got something to do with the call to addTransactionObserver. Maybe those users killed the app while it was in the background and entered the app again after the subscription period ended which caused the addTransactionObserver: to be fired and the notification to arrive.
  If I can get all of my users to get this notification I wouldn't have to run the server calls anymore at the end of the subscription period as they would be fired from the client when needed.</p>
  
  <p>Any insight would sure help understand this puzzle.</p>
  
  <p>Thanks</p>
  
  <p>Roi</p>