There were warez sites that were serving a few hundred copies a day. If we require registration we will prevent the use of those warez distributed serial numbers by allowing only reasonable use. If the warez version needs a serial number. Ref other replies about hacked versions. In the days of DOS 5 in the students' computer room at work I saw a student using an Autocad for DOS that he brought in with him on floppies, hacked so it didn't need a dongle.