Norton Internet Security 2013 - 1 User / 3 PC amazon.com purchase?

They have 2 versions. Boxed and download. I am still using the NIS 2013 30 day trial. But, I want to buy it. Does amazon send you a key for the download version? I don't need to download it since its already installed and running. My other question. Just to be clear. I can install NIS 2013 on 2 other pc's and use the same key correct? Since it says up to 3 PC.