Note: This covers PAID antivirus programs. There are free antivirus programs that, because they are not under a time license, basically don’t expire.

What happens when your paid antivirus subscription expires? In a nutshell: Your antivirus program stops updating itself. But what does that mean and what are the ramifications?

To understand this, first you have to understand how traditional antivirus programs work. I’ve explained this before, but here’s the gist of it: Your antivirus program protects you from malware trying to infect your computer by keeping a list of all known malware. It then compares every file you open, every file you download, every email you get, and so on, to its master list of  “bad guys”.

Because malware creation is such a dynamic subject, the list of known malware grows daily. In order to be effective, your antivirus must have the latest additions to the list of “bad guys” to recognize them. To the degree that it doesn’t have the most recent additions, it won’t be able to detect the most recent infections.

So, a typical antivirus program updates its list at least once a day. Some are configurable and can be set so they update themselves several times a day.

Now, let’s say you have a yearly license in your antivirus and it’s about to expire. Typically you get warnings and pop-up windows that alert you to the fact that your license is about to expire. So what happens if it does? Does the program stop functioning?

No. Typically, your antivirus program still works even if your license has expired. BUT, your vendor will probably not allow updates to happen. So, as days, weeks go by, your antivirus program’s list become more and more outdated. To that degree it won’t be able to detect the latest infections. The more outdated, the less effective. You get the idea.

The above is so true, that an up-to-date,  free antivirus program is probably more effective than a paid expired one. Even if the paid one is fancier and has more features etc., it’s somewhat useless without an up-to-date definitions list.

Normally when your expired antivirus license is renewed, your antivirus will resume updating itself and you will stop getting warnings about it. Sometimes it requires asking the antivirus program to perform an update in order to bring the list up-to-date, and then it resumes doing it automatically from that point on.