You do have to purchase the expansions separately, but every week they have one available to use for free. You can also buy first edition card sets for the expansions that have come out with a second edition (Base set, Intrigue, Seaside, Hinterlands).
Oh, yeah. I remember that now. My parents and I use Android phones, but my brother uses an iPhone. Was trying to get all of them to get the game, but my brother couldn't get it.