Why the assigned license is inactive?

Zyxel_Ivan

If you assign the Nebula Pro Pack to the device, but there's a condition could cause the license inactive:

The Org is not in the Pro Status, and there's other devices in the Org that have no Nebula Pro Pack license.

To activate the license, you can add the Nebula Pro Pack license to all the devices, and the license will activate when the Org turn into the Pro Status.