Lost track of which License key used on which machine

I support a number of Macs running Parallels 9.
We previously purchased licences (in small numbers at retail each time) and installed them, but nobody kept track of which product key was used on which machine.
We KNOW we also have a number of uninstalled licences - but again since nobody kept track we don't know which licence keys are unused (all the boxes were opened so I can't even rely on having a sealed box as an indication).

Is there an easy way for us to see which product key was actually used on a particular machine?
Once we can track this down for all our installed keys, we'll then know which keys we have that have never been used.

Thanks.

 

Hi newbie21,

Your Parallels Desktop license key(s) will be located in the following file: /Library/Preferences/Parallels/licenses.xml

Please check the knowledge base article http://kb.parallels.com/5680 to know which activation key was actually used on a particular Mac.