A method of customizing and modifying program material to tailor it to a receiving end user or client. When program material is to be generated for future customization or modification, an encrypted license tag is associated with the program material. When examining putatively modifiable program material for possible modification, a license tag is decrypted. If clear text results then the putatively modifiable program material is established to be modifiable or customizable. Then the program material is modified or customized to suit the profile of a client or end user who is to receive this customized program material. With the encrypted license tag, the owner of the program material can control the modifications made to his or her program material.