If you want to save a copy of the Avid Studio Library database in order to save the work you put in to tagging and rating media files, you can do so by saving a copy of the NGDatabase.0 directory. This directory can be found here: C:\Users\<your user name>\AppData\Local\Avid\Studio\1.0. To save a copy, right-click on the NGDatabase.0 folder and select Copy. Then Paste the copied folder into a location where you would like to store the back-up.
If you make additional changes to the Library you will need to repeat this process.