nonfree tree?The CTAN archives are currently restructuring their holdings so that files that are 'not free' are held in a separate tree. The definition of what is 'free' (for this purpose) is influenced by, but not exactly the same as the Debian Free Software Guidelines (DFSG).
Material is placed on the nonfree tree if it is not
freely-usable (e.g., if the material is shareware, commercial, or if
its usage is not permitted in certain domains at all, or without
payment). Users of the archive should check that they are entitled to
use material they have retrieved from the nonfree tree.
The Catalogue (one of the prime sources for finding TeX-related material via web search) lists the licence details in each entry in its lists. For details of the licence categories, see its list of licences.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=nonfree