Extreme Management Center does not allow you to update the Access Control Engine License
From Extreme Management Center->Control->Access Control->All Access Control Engines->Select Access Control Engine->Details->Update License does not allow any license to be added there for IA-ES or NMS or NMS-ADV type.
Access Control NAC Extreme Management Center
This is currently being investigated by development as a bug.
As a workaround, boot NAC Manager. Control->Legacy->Nac Manager Once logged into the Java Thick client, Select the Access Control Engine, then Click the Update License under the Configuration Tab. This will automatically import the needed licenses from the Netsight Server within a minute.
Current customers with this issue should log a case with the GTAC in order to get notified of the resolution to this issue.