The IP address is encoded in the license. Please contact support in order detach the key and re-apply the key registration on the server.
In case remote agents are in use , please check to see if those are checking into an IP address or DNS name.
If they are checking into an IP, those agents will lose connectivity until the host information is updated in the remote agent registry.
If the agents are checking into a DNS name, please re-point that to the new IP given to the NMS server.