When you purchase Norton Antivirus then a Product Key avail to you and will be used in installing your Norton Antivirus is your computer. If you purchase Norton from a retail shop then you will get product key on the backside of the redeem card that you will get from antivirus package or through email when you buy it online, Norton Setup With Product Key and you have enter your product key while installing software as unique product key is a proof of subscription in Norton and if you feel any difficulty just call 1866-549-8444 which help you to get right path.