Norton Account devices

I have a subscription which covers 3 devices and I have all 3 used. I want to buy another key that covers three more devices. Can I add them under my current Norton account or will I have to create another one?

Thanks. It would make things a little easier.

I have a subscription which covers 3 devices and I have all 3 used. I want to buy another key that covers three more devices. Can I add them under my current Norton account or will I have to create another one?