Ok, no matter how much protection you can place in a file. Once it is able to be opened, it will be prone to copying.
For example, protected PDF files. Once you are able to print it, you can use a tool like PDF Creator, to print it, and then generate the PDF file however you like.
PDF Creator is free and can be downloaded from:
Another option is to use the GhostScript tool. With it you can generate a new PDF file, from the original one. There is a script that already sets up the GhostScript tool and creates the requireds shortcuts in: