This plugin's own code (everything outside vendor/freemius/) is
licensed under the GPLv2 (or later):

https://www.gnu.org/licenses/gpl-2.0.html

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

The Freemius SDK bundled at vendor/freemius/ carries its own license —
see vendor/freemius/LICENSE.txt.
