Nessus Offline Activation License Already In Use ((install)) -

If you use virtual machine templates, never clone a VM that already has an activated copy of Nessus installed. Install Nessus after deploying and finalizing the hardware/network settings of the new VM.

Locate your specific Nessus product (e.g., Nessus Professional or Nessus Essentials). Click on the asset/product row to view its details.

Run systemctl restart nessusd or service nessusd restart . Preventing the Error in the Future nessus offline activation license already in use

# /opt/nessus/sbin/nessuscli fetch --register-offline /path/to/nessus.license

| | Why It Helps | | :--- | :--- | | Deactivate before uninstalling | Always explicitly deactivate your license if you plan to remove Nessus or move it to another host. This ensures the license is freed in Tenable's system. | | Keep a record of active installations | Maintain a log of which host has which license to avoid accidental reactivations on duplicate machines. | | Avoid frequent host changes | Tenable enforces a reactivation limit (typically within a 90‑day window). If you move the license too often, it may be temporarily locked. | | Use a static hardware environment | Minimize changes to the host's MAC address, network interfaces, and major OS upgrades to prevent the host fingerprint from changing. | | Check license status regularly | Log into your Tenable account and verify that no unnecessary active registrations are still present. | | Plan host changes carefully | If you anticipate frequent migrations (e.g., in a testing environment), contact Tenable to discuss alternative licensing options. | If you use virtual machine templates, never clone

With your reset activation code and your new challenge code, you can now generate the required license file. Go to the Tenable Offline Activation page.

Copying a virtual machine clones the Nessus software but generates a new challenge code on the new host. Click on the asset/product row to view its details

Tenable restricts how many times you can reset a license yourself over a specific timeframe to prevent abuse.

Note: Only the primary contact or product owner can perform this reset.