But only for existing code. If I am a developer and I release this code under GPL: console.log("hello world") And then I as the only contributor to the projec

But only for existing code. If I am a developer and I release this code under GPL: console.log("hello world") And then I as the only contributor to the project releases the code and new changes under a new license: console.log("hello world") console.log("and space") Then that code is under the new license. Yes, you can still use the first version under GPL license. But nothing stops me from granting a new license in addition to GPL. Remember GPL is only a license. It doesnt take away the underlying ownership to the IP. It becomes more problematic of course if the first version isnt 100% written by me. Then I would need any contributors permissions too.