It will last until 60 days after you activated the card! If you log on multiple times in a day, that doesn't matter. Consequently, if you don't log in for several days, those days still count.

Edit: We should group up sometime if we're ever online at the same time. I get confused with who is who when I'm online, but I'm just Scotty Ffgamer so it will be easy to figure out who I am.