What's the deal with "degradation" and lastools?

Many of the LAStool readme files have a paragraph like this:

Please license from [email protected] to use lasclassify
commercially. Please note that the unlicensed version will set
intensity, gps_time, user data, and point source ID to zero,
slightly change the LAS point order, and randomly add a tiny bit of white noise to the points coordinates.

Eg: http://www.cs.unc.edu/~isenburg/lastools/download/lasclassify_README.txt

Other tools add noise in other ways like adding diagonal lines through your output rasters, etc. The free versions are good enough to develop your workflow or verify that the tools are right for you.