How long do webkinz last after purchase?

Forever. Your Webkinz are not removable. I have checked and when you add your Webkinz is added to your account, it's there forever. Also your Webkinz cannot die so it doesn't matter if you treat them terribly or don't go on for 10 years. Some people say that their Webkinz ran away but that is just a lie. The stuffed animal Webkinz lasts for quite a bit. If you love it a lot and sleep with it or carry it around wherever you go, it'll last for about 2 years (that is just a guess). If you don't play with it or love it then it will last a lot longer.