Do I really have to ask for and obtain permission to use 3rd party content? So I'm working on a mod involving different franchises from different copyright holders, and I'm wondering if I have to obtain permission from all of the copyright holders. I know that there are rules set by paradox which require that mod makers obtain permission, but there are music mods on steam containing music from a dozen different copyright holders, and I'm seriously doubting the authors of such mods were able to obtain permission from all of the copyright holders.