The app I'm working on was recently rejected by Apple for containing an auto-renewable subscription. They recommended that we switch to non-renewing subscriptions for our content.
The one thing I can't quite wrap my brain round is how to restore a purchased subscription to a shared device. Apple recommends we don't use user login - something we would like to avoid ourselves. I did come across one solution where unique codes were used between the two devices - to validate a purchased subscription, through a server. But I believe that could be easily pirated, as in theory friends or employees within a company could share these unique codes with one another and avoid paying the subscription charge.
I can't really find much on Google about this, and was curious to know if anyone has been able to successfully implement a non-renewing subscription?