Is GNU License Free?
The GNU General Public License is a free, copyleft license for software and other kinds of works. The licenses for most software and other practical works are designed to take away your freedom to share and change the works.
GNU packages need not be FSF-copyrighted; this is up to the author(s), generally at the time the package is dubbed GNU.
Copyright Papers (Information for Maintainers of GNU Software)
Is GNU license free for commercial use?
Software under the GPL may be run for all purposes, including commercial purposes and even as a tool for creating proprietary software, such as when using GPL-licensed compilers. Users or companies who distribute GPL-licensed works (e.g. software), may charge a fee for copies or give them free of charge.
GNU General Public License - Wikipedia
The GPL is a free software license, and therefore it permits people to use and even redistribute the software without being required to pay anyone a fee for doing so. You can charge people a fee to get a copy from you. You can't require people to pay you when they get a copy from someone else.
Frequently Asked Questions about the GNU Licenses
What is GNU free?
The GNU Free Documentation License is a copyleft license - which means that derivative works must be made available under the same or a similar license. The creators of the license recommend that it is used “principally for works whose purpose is instruction or reference.” Its most prominent user is Wikipedia.
GNU Free Documentation License (GFDL) - Open Definition