Deactivate to Reactivate Unlock Keys
An article telling people how to deactivate a previously activated key so that they can then reactivate the same key on the same machine in order to use aforementioned key in the event of said key no longer operating in a way indicating an "activated" status...
This facility is now available here: https://directorymonitor.com/deactivate2
There is enough information on how to deactivate, you simply use Help → Deactivate from the software.
There is some brief information on deactivating here: https://directorymonitor.com/faq#transfer-unlock-key
There is also a dated article here: https://deventerprise.uservoice.com/knowledgebase/articles/298584-unlocking-directory-monitor