You might think you have deactivated a license, but the process may not have completed successfully. A forgotten active registration on an old virtual machine or a recycled test server can hold the license and prevent its reuse.
The license binds to a (a unique identifier based on the hardware and operating system). Changing the host’s MAC address, migrating to new hardware, or even a major OS upgrade can alter this fingerprint and be interpreted as a new activation request, triggering the error.
If you need immediate scanning, consider switching to (free up to 16 IPs) while waiting for Tenable support to reset your license. nessus offline activation license already in use
You wiped the OS (Windows/Linux) and reinstalled Nessus. The hostname or network configuration changed slightly. The new Challenge Code does not match the old one. Tenable rejects the attempt because your license key is already "Checked out" to the previous OS install.
If you have access to the old machine, or if the license is bound to an active (but wrong) installation, you must break the bind. You might think you have deactivated a license,
: If your license is working, avoid resetting it just to change hardware unless absolutely necessary. Each reset counts toward your allowed quota.
Open your command prompt (Windows) or terminal (Linux) as an administrator/root user and execute the following commands based on your Operating System. For Windows Environments: Open the Command Prompt as an Administrator and type: cd "C:\Program Files\Tenable\Nessus" nessuscli fix --reset Use code with caution. Changing the host’s MAC address, migrating to new
Nessus licenses come with a set validity period and a reset policy. The free Essentials license, for example, usually expires after one year. If the license is already bound to a system that is no longer available, or if you have tried to reset it too many times within a short period, the automated system may lock you out for a while.
"C:\Program Files\Tenable\Nessus\nessuscli.exe" fetch --register-offline nessus.license Use code with caution. Install the plugin package:
Maintain an internal registry mapping your Tenable activation codes to specific hostnames or asset tags to avoid accidentally resetting the wrong production scanner.
Always start by resetting your activation code via the Tenable Support Portal or deactivating the license on the previous host. If those options are unavailable, a local registration reset or obtaining a new code will usually resolve the issue. When performing an offline activation, be meticulous about generating a new challenge code for each installation, ensure version consistency, and follow each step exactly.