The INSTALLED key simply indicates whether or not some "installer" has configured all of the properties that LimeWire needs to run, such as your connection speed, your shared directory, etc.

On Windows, this is set to true when you run InstallShield. On other platforms, LimeWire's own internal setup windows set this to true when they are finished.

Sorry for taking so long to get back to you -- it's just a little hard to keep up.