Disallow - File Save As. prevent my files from being downloaded

Is there any method in which you can prevent people from downloading your web site to disk. I say this because if you have any script that has been paid for it seems only right that this remains soley yours, and not freely available to anyone who visits your site.

When you click on save the site, all files are downloaded to the users desktop, I have seen a method where by a restriction was put on such a task happening, but I am not sure of how to go about this, can anyone help me here?