Today I renewed my NS Premium with a new key on my 3 devices.
I signed in to my Norton Account (web page has a new look) and on each device that was listed I entered the new key.
All my systems were online and it updated the key on each device.
If a system is not online it will check it later.
Works great if you have family members on your account and you can't get physical access.
All done from your Norton Account.
Like the old song - It's So Easy 
Jim 