Stačí kliknout na úvodní stránce na Pomoc/Help:

https://obsproject.com/cs/help

Hned první FAQ:

Is OBS really free?

Absolutely! OBS is open-source software developed by volunteer contributors around the world in their free time. OBS is distributed under the GPLv2 license. The summary of the license is that OBS is free for anyone to use, for any reason. Other developers can use the OBS code in their own projects as long as they obey the guidelines set forth in the GPLv2 license. OBS has no watermarks or other limitations and can be used commercially with no restrictions.

Já vím, je to těžký...