I've noticed that the jQuery plugin "Fancybox" has a peculiar licensing note in its header:
// Licensed GPLv3 for open source use
// or fancyBox Commercial License for commercial use
// Copyright 2017 fancyApps
I get what the author is trying to achieve. They want to allow non-commercial use for free and charge for commercial use. I have been looking for a way to do just that for some of my code as well.
However, can you really restrict the GPLv3 (or MIT for that matter) to a set of conditions (open-source/non-commercial) when GPLv3 itself explicitly permits commercial use? This seems to be a bit of a conflict. Not to mention that someone could fork the code and release it under GPLv3 without those restrictions, if I'm not mistaken.
Would there be a better alternative to achieve this?