OK, the second paper I ran into today is a perfect match for the paper by Khanna and Ranganathan I just dicussed in the Commercial or Proprietary? post. So perfect, in fact, that it I should have really combined them. But since the other post is already infecting the WWW, I'll have to post this update.
Yap wrote up a paper on PaDEL-descriptor: An open source software to calculate molecular descriptors and fingerprints (doi:10.1002/jcc.21707), and Table 2 is quite like Table 1 in the paper by Khanna and Ranganathan. Not only does Yap correctly differentiates between product cost and license, it also details the descriptor type count and descriptor value count. It is a good exercise to compare those two tables yourself.
Yap, C. (2010). PaDEL-descriptor: An open source software to calculate molecular descriptors and fingerprints Journal of Computational Chemistry DOI: 10.1002/jcc.21707