If you go to your "My Products" page on your Cakewalk account it should show you the key to register with Celemony. The download is instructions on how to download and register Melodine. If you bought a Sonar version that included Melodyne it will show up in your account.
Platinum / VS-100 / 12 GB RAM / Win 10 Pro / AMD A8 / MP Touch MonitorsPlatinum / on-board audio / 4 GB RAM /Win 10 Pro / HP dm4 Laptop / stuffTHpfft!