At my office, and at a few of my clients' offices, I have installed Symantec AntiVirus corporate edition. This product requires a license refresh every year. You go to the Symantec website, pay your subscription fee (about $140 for 5 licenses), and they email you a link to a license file.
Actually, that's what used to happen. Now, they've completely screwed up their delivery system, which is why I've been on hold with them for half an hour.