My subscription will expire in a few days. I have bought a product key. Where do I need to enter it to renew?
Activate your Norton protection with a product key ›
Open your Norton device security.
If you see the My Norton window, next to Device Security, click Open.In the Norton product main window, click Help > Account Information > Enter Product Key.
Enter the product key that you received from Norton.
Click Next and follow the on-screen instructions.
https://support.norton.com/sp/en/us/home/current/solutions/v24808774
Norton 360 Classic view -> Help -> Help Center -> Enter Product Key
Note: New product key starts New subscription term.
Wait till ~last day to enter new key or Contact Norton Support...request new key term added to current subscription term.