When a device is assigned to the Un-Managed section it means a few things that you need to be aware of before you set it there.
You are moving the device out of the billing cycle
The device will not be collected from
Device history could be lost if moved from Managed
Devices are tracked by their MAC address Note: If an Un-Managed device changes its IP address and is back on the network it will not be managed due to the MAC address is connected to the MAC address in Un-Managed.