Originally Posted by qtwerp

I had an old version of Lotus 1-2-3 that restricted that to 5 backups somehow. Never figured out how it did it nor cared enough to even try

It was in response to

The disk would have to write to the disk to stop it from being used on another computer. If locked, the software could just not run until a verification program could lock the software to a single PC.

And... a lot of old and current software protection schemes don't make a lot of sense either