Native messaging host for Enpass is an additional component which is required to connect Enpass app with the Firefox WebExtension through native messaging. The exclusive installation of this component is required in case you are using the Store (Bridged) version of Enpass on Windows desktops.
From Firefox v57, the native messaging is the only way to create a connection between the browser extension and Enpass application. Due to the default architecture of the Store version on Windows, Enpass is not capable to connect with the Firefox using the native messaging, and hence the following additional component is required to be installed on your system to create a channel between both.
Version: 5.5.3, Requirements: Firefox 57 or later