I've got at least 3 macs capable of running it, and 2004 is installed on all of them, I didn't keep track of which of the 3 codes I used, so I'm pretty sure I used one of them more than once, and I also moved it from a computer that I sold without any problems or having to deactivate anything. I think you only run into problems if you have two computers using the same code on the same network at the same time.