When attempting to activate Nessus in an offline (air-gapped) environment, users frequently encounter the License already in use error. This occurs because the license was not properly deactivated on a previous instance (e.g., a VM that was destroyed or a scanner that crashed), and the Tenable cloud portal still registers it as active.
This method is fragile and often breaks after software updates.
It turned out that the previous owner of the license had not properly deactivated it before transferring it to me. This oversight led to the license being flagged as "already in use." I was surprised that Tenable's system did not have a more robust process in place to prevent such issues. nessus offline activation license already in use full
: On a machine with internet access, go to the Nessus Offline Registration page . Enter your Activation Code and the Challenge Code you just generated.
Resolving the "Nessus Offline Activation License Already in Use" Error When attempting to activate Nessus in an offline
nessuscli.exe fetch --register-offline "C:\path\to\nessus.license" Summary of Key Constraints
Note: You must be the owner of the code for this option to appear . It turned out that the previous owner of
: Navigate to Products and Activation Codes on the left-hand sidebar.