lost product key

I needed a way to get the product key. my mother bought security 10-device and it's installed on one XP laptop, but not the other computers. This used to be in

XP as a supported OS has been dropped from Norton. we try to keep our old boxes alive as long as possible because computers are expensive for (seemingly) anything worth having (quality of parts, speed, etc).

N360 is listed as a subscription renewal. is this indeed true or is this an erroneous entry?