As the project is GPL’ed I guess they sell a commercial version. GPL is toxic for embedded commercial software. But it can be good marketing to sell the commercial version.

Edit: I meant commercial license

I think they might sell a commercial version as well. It makes sense with the GPL. But I can't really recall that well.

You don't need a commercial version, many projects get away with selling just a commercial license to the same version. As long as they have the rights to relicense this works fine.