DRM question - backing up license

i am reviewing a ppv site that also offers pay to own videos that are yours to keep but do use DRM. while they play with no expiration date, they don’t allow you to back up the licenses. i was under the impression it’s a good idea to back up your license in case the original corrupts, but i could be 100% mistaken as i know little about DRM.

so can anyone here explain what backing up the license actually does?

thanks!