Update your antivirus program if an update wasn't performed during the install or you didn't have an Internet connection available to you during the installation.

Update your virus definitions, the "signatures" that identify known viruses. When you buy your antivirus program, you'll receive a subscription for an update service which will allow you to download any new virus definitions. The update subscription is often for a year, so eventually you'll have to purchase a new subscription.

Upgrade your antivirus program. Antivirus companies release new versions of their software every few years. The new version will have features not available in your current system. Purchase these new upgraded programs and you'll have the latest features, enhanced virus protection and a fresh subscription for virus definition updates.

Maintain your antivirus software by scheduling automatic updates. If you rely on manual updates, you can easily forget to perform them and your virus definitions can fall behind