I have had a few devices I'm sure that I have sold or traded in where I didn't know this. Oh wellApple does it. If you have not had a claim, they give you a pro-rated amount back. They are very generous about it to. I had returned an iPad and forgot I purchased AC+. I called them a few weeks ago and they refunded me the whole amount since I returned it within 30 days....even though it was a year later when I called.