LGPL open source project - condition on invoking license (no right to use the software) on certain modifications. Is it possible?

Question

Released a software under LGPL license.

Now added also a paid license check to it, so users can also upgrade to commercial license.

However, I think some users can remove the check and re-release it under LGPL

Can I somehow prohibit it? If license check code parts are modified, users rights, license (LGPL) are completely removed and there is not right to use this modified software.

How can I protect against this modification of code?

With close source it can be cracked, but with Open Source it would be very easy to remove it and release in the Internet as a new project.

What are your suggestions?

Was thinking to add a extra clause in "commons clause" in LGPL that would say:

"modification to license check code, removes and rights to use this software"

"Unauthorized further distribution may result in severe civil and criminal penalties, and will be prosecuted to the maximum extent possible under the law."

Answer 1

If you have released software under the LGPL license, you have given all recipients the right to modify this software for any purpose, including removing or adding features in a manner that you don't like.

If you don't want that, you should not release your commercial features under the LGPL. Things you could consider doing:

• Publish the software under a different license. This is what you're thinking about. But note that you can't just add such license terms.

  • Either, the license is still the LGPL with some extra terms. But then, the terms of the LGPLv3 allow recipients to remove the additional restrictions.
  • Or, this is an entirely separate license. But then it would no longer be the LGPL, and no longer be an Open Source license.

  Whether such additional terms create a separate license or can be removed from the license is currently being litigated in the US in the context of the Neo4J database, which added the "Commons Clause" restrictions to the AGPLv3. See a discussion of the case from the Software Freedom Conservancy here: https://sfconservancy.org/blog/2022/mar/30/neo4j-v-purethink-open-source-affero-gpl/

• Remove the restricted features from the LGPL version and maintain a separate commercial version, or implement the commercial features as a plugin. This is sometimes known as an “open core” business model.

  Due to the limited copyleft effect of the LGPL, you can still combine the proprietary parts and the LGPL-covered parts into a single program, but doing so may be confusing for users. It should be absolutely clear which parts are LGPL-covered, and which are your proprietary parts that cannot be modified. However, you would not be able to prevent recipients from using the LGPL-covered parts without your proprietary components, i.e. they would always be able to remove any licensing checks etc.

More generally, it could make sense to think about why you want to publish any part of the software as Open Source. Sometimes, Open Source licensing is a good business decision, sometimes it isn't. If you want to control what users can do with the software, Open Source licensing is not a good fit for your goals.