Keet (1985, pp. 117–118) says there are five types of software piracy thieves:
This makes software piracy policing difficult. Software manufacturers started policing activities by "placing a notice in or on the package or manual supplied with the software limiting the user in what he or she can do to or with the program" (Thomas, 1985, p. 136). However, many users ignore these notices. Additionally, Thomas (1985, p. 137) says, "There is no way to prove that the purchaser actually saw the limitations or that he or she agreed to them." He further states that it is difficult to legally restrict or control what is done with software after it has been purchased.