Assuming you have a valid license, you will likely need to contact Adobe support and I believe they have a capability to take your information and provide you a code for manual activation.
Helpful and Handy Links
Yes, I have a valid license. But this is where my confusion lies. I'm not being prompted to activate, just register. And it says explicitly on Adobe's website that you have no choice but to activate online. So again, I don't know if it's activated or not.
Contact Support - they can get you activated without being connected. They run into this with installs of FrameMaker all the time that are inside government Defense Ministries and defense industry contractors that are cut off from the outside world for security.
Be aware that Deactivate is often greyed out for a while after opening RoboHelp. Leave it a few minutes and it should then show as Activated.
There is information on Adobe's site about activation, search on that term. There are far fewer exceptions to having to activate with RoboHelp 9 and it is essentially limited to a few very high security scenarios.
RoboHelp 9 automatically activates if it can so my guess is your copy is activated.
See www.grainge.org for RoboHelp and Authoring tips