The GPL license allows you to sell GPL'ed software, it's just that any changes you make to it have to be open source also, and have to be licensed under the GPL which means anybody can compile it for free, give it away for free, etc.

Cycles license specifically says it can be used in commercial software:

"Cycles is an physically based production renderer developed by the Blender project.

The source code is available under the Apache License v2, and can be integrated in open source and commercial software. Cycles is natively integrated in Blender, Poser, and Rhino. The Cycles4D plugin for Cinema4D and a plugin for 3ds Max are available as well." (From https://www.cycles-renderer.org/ )