[didgetmaster]

>The period is not fixed for the open source licenses, so if you change the license for the latest version, the old versions are still under AGPL. Therefore, even if I change the license for mold, anyone can just fork the old open source version and continue to develop it easily.

This is a major issue for anyone considering offering their software with an open source license. There are many licenses to choose from and you have to get the first one right. You can't just pick one and later switch it to something more suitable.

[eikenberry]

You can just pick one later as long as you understand that you are doing it for it's future impact and not it's current impact. Of course people who want the old license will just fork your old version as they are pretty much the same as you just re-licensed. But 5 years down the road your forking your old version won't be meaningful as your product will have evolved significantly and not be the same product anymore. Copyright licenses are long term by their nature (ridiculously long term) and their impact is best understood in those terms.