> Many years ago, a friend of mine was asked to rerelease a copylefted program under noncopyleft terms, and he responded more or less like this: > > > "Sometimes I work on free software, and sometimes I work on proprietary software---but when I work on proprietary software, I expect to get paid." > > He was willing to share his work with a community that shares software, but saw no reason to give a handout to a business making products that would be off-limits to our community. His goal was different from mine, but he decided that the GNU GPL was useful for his goal too.

The approach is far more common in other kinds of licensed, creative work. Creative Commons' choice to standardized noncommercial license terms helped make commercial-noncommercial licensing familiar in photography, illustration, music, and so on.

The model has gone by a few names. Those researching should search on "selling exceptions" and "dual licensing", too.

I'm doing what I can to popularize through License Zero (https://licensezero.com).