I've never done this myself but I think LM are quite good about it. To avoid this in future, make sure you perform an uninstall properly, in my experience this avoids you having to contact LM.
Ian
I believe it is recommended to use the normal Windows control Panel to uninstall the simulator, and not the setup file.
The standard un-installation method will free the licence automatically.
Gotta love chinese whispers..... I was told the exact opposite;-)