I am surprised that the Company Symantec and Amazon allow such a possibility. I had imagined buying a disc from Symantec would not allow such third party use of licences. If indeed is what is happening here.
Symantec/Norton loses control of its products when they are sold. They can still control the licenses but that doesn't prevent some less that honest folks from doing 'things'
If it sounds too good to be ture, it isn't - when you're talking the Internet and transactions.
Stay well and surf safe