This is a program that many people first tend to use because it's free. You don't need a code or serial number. Well, I think you should just pay for your virus protection because this program is not helpful.
At first, it seems useful. It updates and it notifies you to scan your computer like any other virus protection. Sometimes it'll detect viruses, trojans, and malware, but from my experience, I can tell you that it lets a lot of these slip through the cracks. I used this for about a year before I got fed up with it. AVG doesn't even stop you from downloading something that could be particularly dangerous. It tells you what sites you can go on, but does not tell you that there is somethign potentially dangerous in a file and by the time you find out, it's too late to fix it.
I'd suggest that you find a better virus protection. There are plenty of free trials around for you to try them out instead of making you just go out and buy one you may or may not like, so take it slow and find the right protection for you. I suggest BitDefender above others, but then again, that's just me.