“Many people misunderstand Free Software and the GNU General Public License. Many people equate the GPL to the boogeyman, because it’s viral, and that sounds like a bad thing. Here’s what viral licensing means: GPL software has the restrictions that it has, and that’s it. The GPL is quite restrictive on developers, not at all on end users. (More on that in a minute.) Regardless, GPL software has the restrictions that it has, but it can never become more restrictive. An upgrade can’t take away freedoms that I enjoyed with an older version.
A side effect of this is that, if I write a GPL program and then lose interest, and someone else picks it up and continues development, they are forced to release their version under the GPL. A new developer can’t take away freedoms that I enjoyed with the old version either.”