This only applies for Management Center virtual appliance.
There is a new license purchase that upgrades the number of devices that can be managed by the Management Center.
This new license is on a new serial number and there is an existing Management Center already running that has limited or lower number of devices that can be managed.
There is a requirement to use a new license.
In order for the existing Management Center to use the new license, the virtual appliance would need to be rebuilt with a new serial number.