Home edition is free, which you are able to use as long as you want and you don't even get a reminder pop-up from my experience so far. $70/year is for the professional version.
Checking out their download page[0] does reveal some limits on the home edition - 12 sessions, 2 ssh tunnels (I wish I knew if those were "simultaneous" or "saved"), a couple of other things - but I haven't run up against these limits yet. I do think that if I was doing something that required more than twelve simultaneous ssh sessions, I would have already switched over to my Linux installation. SSHing from Windows is something I generally do for small things.
