How to share a licence with a friend

How to share a licence with a friend.
Norton tells you what to do to share a licence, but does not give explicit advice for the person receiving the extra licence. Once they have downloaded the Norton Android app, for example, do they have to sign in for it to work? Surely the main account holder is not supposed to share their log in details. Are they supposed to share the product key with the new user? Can someone clarify please.

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