Thanks Jelle,
Dit vond ik ook nog op een ander forum:
"Here's the scoop: You can install it on as many machines as you want, but there are several catches to this.
First, you can only run one copy at a time on a network. For example, say you have a studio with three Mac Pros all networked together and all running Logic. You will only be able to open Logic on one computer at a time. If you try to open Logic on another networked machine, you will get a message telling you that you are already running a copy of Logic with an identical serial number on that network.
Second, every time you update Logic using automatic update a message is silently sent to Apple with your serial number and machine ID enclosed. After you install Logic on so many machines (nobody is exacly sure what that magic number is) your serial number will be "black-listed". What this means is that your serial is added to a list of serials embedded in each Logic update released after you have been "black-listed". When you try to install a new update (even doing so offline) you will be asked to enter a new serial number before you can open Logic again. I have installed my copy, an NFR version, on 4 machines with no trouble, but I've decided not to push my luck any farther."