Licencing: release the same software with double licence

Question

In my free time, I develop (alone, sigh) a project, in particoular an application library. I've released it using GPL v3.

At this time, this project has come very useful for a job. I'd like to release my OSS library toghether with the application using the same GPL v3 licence, with the exception that it can be linked for the specific application, or for the specific application vendor.

AFAIK, the copyright owner can handle the entire source and licencing it, I did it; and probably the licence owner could cut&paste its own code, change its licence and use for other projects, isn't? But an GPL'ed library cannot be linked with a proprietary software, right? But software could be double-licenced, as MySQL does.

So the question is: what should I do to allow the distribution of my GPL'ed library with a proprietary software, being the copyright owner?

Answer 1

Well, you don't have to ask yourself for permission to use your library in your other projects. That would be… schizophrenic.

If you are the only owner of the library (that is you have not accepted any outside contributions), then you can distribute it any way you want: as a separate project, or as a component of some bigger project.

You offered certain terms of use of your library (GPLv3). It doesn't mean that you can't make another offer with different terms (whatever licensing terms you find suitable for that other project).

If you have accepted outside contributions, and you are not the sole owner of the library, then consider changing the license to LGPLv3. It's simpler than negotiating an exception regarding your other project with every contributor.