What happens when an open source project changes it's license?

Question

Let's say a team plans on developing an application based on an open source project named "FreeApp". We are developing this application with the ultimate goal of heavily modifying and re-distributing FreeApp under a different, branded name, as a paid application. The current license allows this.

My question is, years/months down the road, if FreeApp decides to make a major change to the license that prohibits our particular usage of their software (if it matters: we would start and end with version "1.0" - the license change would come about around "v5.7"), what would our worst case scenario be? Unaffected? No future redistribution? Inform clients they are in violation of some obscure law and must delete our application?

Lots of related questions, nothing relevant to this.

Thanks!

Answer 1

In a nutshell, an open-source license can't be revoked.

If an application has been released under the terms of any standard open-source license (any license from http://www.opensource.org/ is safe), the original authors cannot legally revoke that license. The only worst-case scenario would be if it turned out they did not legally have the right to release the code in the first place.

If the original authors change the license to something you don't like, you still have full rights to any versions released prior to that date under an open-source license.

Answer 2

Unaffected. You would no longer be able to incorporate new versions of FreeApp into your PayApp. But the code you already received remains under the license as it stood when you got it.

The important thing is that, when you receive a copy of source code with a particular license, you have been granted that license. So long as the license doesn't have a revocation clause, it's permanent.