Have you lost your Mac OS X Server Installation Serial Number? If you have lost the OS X Server Installation serial number or have a Mac OS X Server and you need to reinstall it, but you don’t know what the installation serial number is, just follow these quick and easy instructions to retrieve it from your Mac OS X Server:
1.) Open Terminal and type the following command: sudo /System/Library/ServerSetup/serverserialnumberutil -get
2.) Press <Return> or <enter>.
3.) You should see something that looks like the following:
That’s it, you should now have the serial you either lost or never knew.