Thanks for the feedback, you're absolutely right and I'll make it more clear on the landing page. There might be some new functionality in the future that would make up a paid service, but all of the current functionality is meant to be free.
It's always annoying when you signup for free stuff and then a year later they remove free completely, basically a bait and switch.
I'd also put that information on your "about" page. (Only on the about page, if you want to keep it off the front page.)
It's certainly something that occurred to me looking through the options.