This does not provide a service visible to the user, but is essential for the management of Remository. It is activated by Joomla when options are saved. This is important so that any change in the Remository options that requires some processing can be handled. For example, if you change the option for adding an ID to file names, Remository has to rename all affected files. (This mechanism is discussed further here).
The Remository Extension plugin is automatically installed and published when Remository is installed. It should be kept installed and published while Remository is in use.