Before you can start using your Norton subscription with this new key -2027

I bought a Norton 360 Premium subscription on Amazon. When it was time to renew I opened the desktop app, signed in to My Norton account in the app, entered the new product key (Help, Enter Product Key in bottom right) and got this message:

 "Before you can start using your Norton subscription with this new key, we'll need some additional information to register it. Please enroll at norton.com/setup. (-2027)"

Clicking on the norton.com/setup link took me to the Norton website Login page. I logged in and could not find a way to register the new key. This is what finally worked for me:

On FIRST computer, had to open web browser, login to Norton site BEFORE opening Norton app on computer, then in app Signin,
  Help, Enter Product Key, enter the new key, it fails with the above message, clicked link to Norton.com/setup

  That web page provided a text box to enter the new key
  Enter Product Key. The version I bought requires Auto-Renewal, went through that setup then back to
  Manage Subscriptions, had to refresh the screen a couple of times before the new Subscription showed,
  then Canceled the Auto-Renewal (multiple screens involved with that process).

Then I was able to enter the new Key in the desktop app on all the computers.

Thanks Nathan! When I clicked on the LINK "norton.com/setup" in the message in the app, it took me to a login site/screen. When I typed it in the address bar as you suggested, without being logged in, it went to an "Enter a Product Key" site/screen. Hopefully I'll remember that 15 months from now.

Next time when activating a Norton Product Key just go straight to norton.com/setup or norton.com/enroll and activate the key, after that you can indeed put in the key in the Norton on your PC (Help, Enter Product Key) and deactivate Automatic Renewal on my.norton.com