You get a key with each copy that gives you 30 days. Order 12 copies of this and get a year of play for $60 plus shipping. Normally, a year subscription costs almost $150. I have done multiple keys on an account, so I know it works.
Also, the devs have announced that they are not going to do the paid expansion next year after all. All planned content from that expansion will instead be rolled out with normal quarterly (approximately) updates.
RagManX