I know that a few pieces of software distributed on floppy showed a warning if it detected it was previously installed (which wrote to some file on the disk, gi

I know that a few pieces of software distributed on floppy showed a warning if it detected it was previously installed (which wrote to some file on the disk, given it wasn't write protected). Which basically amounted to a sternly-written paragraph to say that they're using honor system to make sure you follow the rules.