I don't pay for it, but perhaps I got grandfathered in as an early adopter?

As far as I'm aware, you just need to download the Plex Media Server software for your computer and point it to where your files are. Then you install the app on your Google TV. I think the paid account is for early access to new features and/or remote media playback on mobile devices, but I could be wrong... Either way I don't think you actually need an account to get the thing working. You can still point the app to where the server is on your network and it'll take care of everything.

Seriously, it's fantastic software. The Google TV app is probably the furthest behind, but it's still very good and has actually seen updates and significant improvements unlike every other Google TV app I've used...