You'll need two files: keys database and AACS dynamic library.
Keys database: get the file
Windows: put it in %APPDATA%/aacs/ . How to find where %appdata% dir is?
Mac OS: put it in ~/.config/aacs/
Linux: put it in ~/.config/aacs/
AACS dynamic library
Windows 32bit: put that file in your VLC directory
Mac OS: right-click on VLC, choose "Show package contents" and put that file in Contents/MacOS/lib directory
Linux 32bit: put that file in VLC folder (or in LD_LIBRARY_PATH, usually /usr/lib/)
Linux 64bit: put that file in VLC folder (or in LD_LIBRARY_PATH, usually /usr/lib64/)