Two eth cards - which Host ID to specify when applying for license?

I have come to understand that the Host ID needed when applying for a license is the MAC address of the Ethernet card installed on the host. In my case I have two eth cards - one active with assigned IP and one inactive and unused. The cvx_version() program returns the Host ID (MAC addr) of the unused nic.

My question is - is it important that the Host ID I use for the license registration have an active IP or is the Host ID simply used for accounting purposes and therefore it does not matter which of the two Host IDs I submit with my license application?

Thanks for any help with this,