A watermark can be included in protected PDFs and images. The watermark shows the user that has opened the protected document. This way, it is possible to know the user that has printed the document or taken an screenshot. In the images it is also included the time when the image was opened. In this case, it is also possible to know approximately the time when the image was printed.
The watermark can be configured in the Option's screen during the creation of a protection policy: