As far as I'm aware there is still a free version, but the MBAM site doesn't make a big deal about it as rightly they are trying to sell the paid version to support their research and development.
s you say the free to try may well just become the free version after the trial period, which I can find nothing about the duration, but if you did have to pay it is a one off payment rather than an annual license (at least it is so far).