Both applications use a database file shipped with LDD, which is a file called db.lif. This file contains information of all bricks, geometry, materials etc, and having the file in your machine is mandatory for Blueprint and Bluerender.

The applications first try to locate the database file in it's default position, which is:

C:\Users\USERNAME\AppData\Roaming\LEGO Company\LEGO Digital Designer\db.lif

If it's not found there, then the programs will prompt the user for manual location. This way you can copy the file to a machine without installing LDD (if you don't have the rights, for example) and still use the applications.

The location of the file is then stored in the configuration files.