Thanks for the feedback. We're really focused on facilitating teamwork. It's normally something intangible and we're trying to make it visible which will hopefully in turn make it contagious.
I will take a look into how a one-off fee model would work.
And if I was you, I would much rather make enough money to pay the bills, than play the freemium lottery.
And Taskmessenger is all about adding value to a project - something that you should be proud to charge for.