Yes, this is an exception because of the high number of Mac users who are working on two operating systems. This option is only valid for the interim until most users are working with Mac OS X only. Therefore, you can use REAKTOR for Mac on a laptop and a desktop, with both OS X and OS 9. This means you get up to 4 authorization keys. However, they will only function on the two computers. You will not be able to install and authorize REAKTOR on four independent computers.