GoG, and physical games are only licenses as well. If you have any physical games from the era of instruction manuals you can find it laid out clearly inside, generally towards the end.
But GoG’s offline installers and physical games can’t be taken from you by the publisher etc (servers for online games and updates aside).
Neither can installed copies of games if you write protect the files, back them up where the launcher can’t get to them, etc. Licensing, DRM, and legality really aren’t the defining factors here. There are shades of better or worse, but at the end of the day it’s about simply being able to back up the media in a form that can’t be touched by the corporations.
This is my biggest personal disillusionment and frustration with the world. If companies would commit to open interoperable data standards and allowing access through APIs, there’s so many things in life that would be better. We could have our tech actually work for us.