Can You Use GPL In Closed Source When it comes to software development and licensing, the question of using GPL-licensed software in closed-source projects often arises. The GNU General Public License (GPL) is designed to promote the sharing of software source code and ensure that derivative works are also released under the same license.
They are permitted to maintain source code confidentiality; nevertheless, once they decide to distribute it, GPL requirements must be acknowledged, and the source code disclosed accordingly.
While it’s nice to be a contributor as a closed source maintainer to an open source GPL library it’s not mandatory it just shows you can play nice and give back to the community.