I got a dockstar 2-3 months ago. I cannot swear, but I think the installation "wizard" stated that it was free for the first year. I cannot locate anything that seems to indicate that it is not free for life now (and the documentation just was not updated). I have not provided them any personal information or payment information so there is no way that they could charge me.
Looking through my account there, I do not see anything that mentions a fee or subscription or expiration. (this access is at
http://dockstar.pogoplug.com)
It also works relatively well with streaming to my PS3 and is easily read by my WDTV Live.