On Wed, 2011-04-13 at 14:36 +0200, Erwan David wrote: > The author (or the copyright owner, depending of the country) may > change the licence at any moment. > However, he cannot remove rights to people who obtained the software > under GPL. a recent example is NoMachine NX4...they changed to closed source http://www.nomachine.com/news-read.php?idnews=330