How to Renew Online Installed NIS with Store Purchased Product Key

Hello, I need to renew my current version of NIS that I installed from the Norton website. All the options I'm given are to pick a dollar value of the renewal I want. I want to input a store purchased Product Key that I haven't used yet. I installed from the web because I could not install from the disc. I'm running Windows 8.1 Pro Update (the latest and greatest.) Please advise.