If you open Cinema preferences you'll see a button at the bottom of the dialogue that's labeled "Open preferences folder." If you click on that it'll open a folder that has a library folder inside. When you open the library folder you'll find a file called "user.lib4d". Copy that file to the same location on your other machines. It includes any bitmaps that may be in your materials.
I have a slightly different issue. As I am experiencing disk space issues, I am just curious to know if the library files (*.lib4d) I have in previous version can be used for the installation of newer version. In short can I refer and use same R14 library folder for R15 installation?