1. Renewal Email
(Support/Top page)

... AntiVirus 3 PC, but wish to switch to Norton AntiVirus 5 PC, or Norton 360 3 PC, you can. If you change the number of users, your unexpired time will not be added to the year you purchased. If you switch ...

2. Why does the new software say it's expired?
(Support/Download and Installation)

If you've just installed, and it says it's expired, or say it has any amount of time less than a year, what has happened is the install has found an old expired product key, and decided to use that instead ...