Where are Plugin Manager disabled plugins stored?

When you use Plugin Manager to disable a plugin, the plugin file is moved to the directory /Library/Application Support/Digital Rebellion/Pro Maintenance Tools/Plugin Manager Disabled Plugins.

If your trial expires and you do not register the software, you will need to manually move files that you would like to enable back to their proper location. The files are stored in the disabled plugins folder under their original hierarchy so it's easy to see where the file came from.