I was originally promised IPAM already had this feature but, surprise, sales lied. Shocking, I know. 
So here it is. Prevent folks from plugging into a subnet and automatically retrieving an IP, UNLESS their MAC address was previously registered. If it was, they'll get the pre-defined IP address. This allows one to set DHCP on all hosts that have had their MAC addresses registered. It will make things exponentially easier vs having to configure each individual machine's IP information. And, it will secure the subnet from rogue hosts trying to gain access to the hosts.
Please let me know whether you require further information.
Regards.