What Is an Activation Code? An activation code (also known as a license key or product key) is a unique alphanumeric string used to unlock the full version of Kaspersky antivirus software. It verifies that you have purchased a legitimate license, granting you access to real-time protection, malware scans, firewall features, and automatic updates for a specific period (e.g., 1 year, 2 years, or 3 years).