Server license key is missing, invalid or has expired.

[Tobias Plaputta]

Hello!
I have been using VNC Free Edition and now thought about upgrading.
I wanted to use the 30 Day trial and so I have installed the personal
server on my remote PC using VNC.
After the installation (well, after I have chosen to register vnc as
service and so and then clicked "Next>>") the connection broke down.
No problem I though. I tried to reconnect to my remote PC using the
personal viewer and received the message "Server license key is missing,
invalid or has expired.[...]".
I have never used a VNC trial before.
Is there any way to activate the server via remote?
There is neither a keyboard nor a display nearby the remote PC so it would
be kind of stressful to directly access the PC.
Kind regards, Tobias