For a site that is no longer accepting new content, you might want to put it into "read only" mode, keeping the content available online for users but preventing users from logging in or posting new content.
You will also want to optimise the site to remove unnecessarily functionality for guests and to improve performance.
There are quite a few configuration changes you can make using the admin UI alone, but there are some elements you will need help to change - which is where this addon...