wger Workout Manager is Free/Libre Open Source Software (FLOSS).
wger Workout Manager is released under the Affero GNU General Public License (AGPL) Version 3+ and can (under the conditions of the license) be used, modified and distributed (also with modifications) without restrictions.
A copy the license text is contained in every wger Workout Manager release (LICENSE.txt) and can be read online on the website of the GNU project.