If you cloned a VM and want both VMs to work independently (each with its own license), you cannot simply clone. You must reset the fingerprint.
Copy the challenge code.
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 nessus offline activation license already in use
: Only the Primary Contact or Product Owner can reset activation codes in the Tenable Community. If you cloned a VM and want both
On your offline machine, you need a fresh challenge code to link with your reset activation code. /opt/nessus/sbin/nessuscli fetch --challenge Tenable Discussions : Only the Primary Contact or
You uninstalled Nessus and tried to reinstall it on the same machine, but the server didn't "release" the old hardware ID.