Can I detect if a program is posted over network

[Matrix_zero]

I am about to start selling my new application to several municipalities, and it will be sold on a per computer basis. To activate their software they will need to obtain a product key which i will give them based on their hard drive ID number. The problem i have is that if they post the program over a network everyone can access the program, and only pay for 1 license... not to say that they would do this, i just want to be sure.

Does anyone have any ideas besides re-writing the registration module?

 

[Matrix_zero]

More info

Just to give you some more info... the BE may be on a network.