This needs to be communicated better. I signed up, created a session, but when I tried to make the session private I got the message about being over the limit and assumed that the attempt to make the session private failed and it remained public, so I deleted it and that was the end of the tryout for me.
Also, I was alarmed that my session started off as publically listed and viewable as it was created from a private codebase. Ideally it wouldn't ever be public unless explicitly set to be.