Does anyone know how to actually activate this license? And does it require the OS to be Professional prior to activation?

It seems to be caused by the driver for: Qualcomm Atheros AR8151 PCI-E Gigabit Ethernet Controller (NDIS 6.30)

Try downloading the newest available driver from here: http://devid.info/p466934

It seems to be caused by Marvell Storage Controller.
Open "Computer Management" > Select "Device Manager" > Expand "Storage Controllers"

You should see the Marvell’s controller, right-click on...