since 2.6r7 nauty has a free license (Apache 2.0) see http://pallini.di.uniroma1.it/
commit bb14cf9a8b120a20a2874241b08650920991dabf (HEAD -> master, origin/master, origin/HEAD) Author: Christoph Junghans <junghans@gentoo.org> Date: Mon Jul 10 22:07:39 2017 -0600 sci-mathematics/nauty: version bump Package-Manager: Portage-2.3.6, Repoman-2.3.1