To avoid ever seeing "license already in use" again, implement these three policies:
Your physical server’s network card died. You replaced the NIC or moved the hard drive to entirely new hardware. The Challenge Code (based on the old NIC) is no longer valid, but Tenable’s servers still show that your license key is tied to that dead hardware’s Challenge Code.
If you need immediate scanning, consider switching to Nessus Essentials (free up to 16 IPs) while waiting for Tenable support to reset your license.
When attempting a Tenable Nessus offline activation, the error "license already in use" typically indicates that your activation code is still linked to a previous installation or a different hardware ID. Because Nessus licenses are locked to a single host, you must manually release the code before it can be applied to a new offline environment. Why This Error Occurs
Nessus ties your activation code to a specific Challenge Code generated by your machine. If you previously registered the code—even on the same machine before a reinstall—the Tenable registration server sees it as "in use" and prevents a new license file from being generated. Step 1: Reset the Activation Code
The most effective way to clear this error is through the Tenable Community portal.
Log In: Sign in to the Tenable Community Support Portal using your administrator credentials.
Navigate to Products: Select My Products from the upper right corner. nessus offline activation license already in use
Manage Product: Find your Nessus Professional license and click Manage Product.
Reset Activation: Click the Reset Product Activation link. Confirm the action when prompted. This "unlinks" the code from any previous host, making it available for a fresh offline registration. Step 2: Generate a New Challenge Code
Once the code is reset, return to your offline machine to generate a new challenge string. Linux: Run /opt/nessus/sbin/nessuscli fetch --challenge.
Windows: Run C:\Program Files\Tenable\Nessus\nessuscli.exe fetch --challenge in an elevated command prompt.
macOS: Run /Library/Nessus/run/sbin/nessuscli fetch --challenge. Step 3: Complete Offline Registration
With the reset activation code and the new challenge code, you can now generate the nessus.license file.
Visit the Tenable Offline Registration Page on a machine with internet access. Enter your Challenge Code and Activation Code. To avoid ever seeing "license already in use"
Download the nessus.license file and the plugin archive (all-2.0.tar.gz).
Transfer these to your offline machine and register the license using: Command: nessuscli fetch --register-offline nessus.license. Additional Troubleshooting
Full Reset: If the software itself is stuck in a weird state, you can use the nessuscli fix --reset command to wipe existing registration settings on the local host before trying again.
Plugin Delays: After successful activation, it may take roughly 10 minutes for the Plugin Set to populate in the web interface.
To resolve the "license already in use" error during a Nessus offline activation, you must reset the activation code
in the Tenable portal before the offline registration page will accept it again
. This happens because the license is still tied to a previous installation or a failed registration attempt. E-SPIN Group 1. Reset the Activation Code When attempting a Tenable Nessus offline activation ,
Since you are performing an offline activation, Tenable’s servers believe the code is active on another machine. Tenable Community Portal Navigate to My Products and select your Nessus subscription. Find the specific Activation Code you are trying to use. Manage/Reset
(or the "X" / "Reset" button) next to the code. This unlinks the code from any current hardware ID. E-SPIN Group 2. Generate the Offline License File Once the code is reset, you can proceed with the standard offline registration process Get Challenge Code
: On your offline Nessus scanner, run the following command (or find it in the UI under Settings):
C:\Program Files\Tenable\Nessus\nessuscli.exe fetch --challenge /opt/nessus/sbin/nessuscli fetch --challenge Access Activation Page : From a machine with internet access, go to the Nessus Offline Registration page Submit Details : Enter the Challenge Code from your scanner and your Activation Code Download License : Click "Submit" to receive your nessus.license file and the plugin download link. 3. Apply the License nessus.license
file to your offline scanner and register it using the command line: nessuscli fetch --register-offline nessus.license Alternatively, upload it via the Nessus web interface under Settings > Registration > Offline Additional Troubleshooting Resources Official Docs Community Fixes Plugin Updates Tenable Documentation Tenable Offline Installation Guide
provides the step-by-step requirements for challenge codes and license application. For transferring licenses between hosts, refer to the License Transfer instructions to avoid seat conflicts. Tenable Knowledge Base explains common reasons for the 'Code in Use' error. Tenable Discussions
often suggest checking for hidden proxy settings if the reset doesn't immediately reflect.
Offline scanners require manual plugin updates. Follow the guide at Tenable Software Updates Are you performing a fresh installation , or are you trying to an existing license to a new air-gapped machine? Update License Offline (Tenable Nessus 10.11)