I have a collection of Genealogy cd's, they are basically databases of Births, Deaths and Marriages. 2 of the newer discs have protection of some kind on them, you can copy the disc but get limits on the number of searches when installed.
Its hard for me to describe, because I havent hit this limitation yet but thought I would ask if anyone knows how or what this limitation is. The discs use the companies software called "Digger".
Edit : Just installed and had a look, it asks you to register the disc. You can do 20 searches before you cant use it.