How do I change AppleCare+ ownership?

I purchased a MacBook Pro 13", one of the smaller ones with no ethernet port, from an individual online and when I got it I checked the warranty status and saw that it is covered for another year and a half meaning the original owner purchased AppleCare for the machine. I don't know the process if I have to have it fixed but don't I have to have the coverage in my name for it to be valid? So, how do I change the AppleCare coverage and or the product registration over to my name when I don't even know who the original owner was and all I have for proof of purchase is an online sales receipt from the eBay seller and that doesn't list a name either.