I prefer open source software - the license applied to an open source software project lets me know up front what my usage rights and obligations are.

The Numenta Platform for Intelligent Computing (NuPIC) is free for academic and non-commercial research use, but there is so far no definitive information on commercial licensing costs. As a result of this, even though I like the ideas behind NuPIC, I spend relatively little time playing with the examples. I very much enjoyed Jeff Hawkin's book On Intelligence (Amazon purchase link) and I will probably devote a lot more time to experimenting with NuPIC when all of the licensing issues are nailed down.