Actually, Bit, this raised another intruiging ethical question/scenario: A client contacts you to do some modelling work that's an update to an existing file. Along with the model, they send you the program and a registration number that will allow you to install the needed software to do the job, with the understanding that you'll delete it after the job is completed. Assuming your own ethical standards are such that you actually do, is it proper for the client to do what they did?