Licensing aren't physical, but they are individual and are traded. They have an inherent value, and are protected as any other property.
Copied material worth nothing, those are just bits. The license to use those bits, however, is lost on copying, that's why you cannot use both the original and a backup or replacement copy at the same time. You still have only 1 license.They lose no license in the process of copied material, which is why you can't be charged for downloading a copy of something if