Well,

As a general rule if it can be seen or read it can be copied. This is why there has never yet been a successful DRM solution.

I would suggest that you should include the humble "dongle" in your research. By including a hardware element, you make life a lot more difficult, particularly if the hardware device contains required decryption and/or functionality software.

This solution is relatively expensive, and would meet considerable resistance from the general public, but I have used it for high end CAD and Systems Design software. Perhaps introducing a card into the machine rather than an external device?

It is all a matter of costs and revenues. Like how many do you want to protect and what are they worth.

You will never stop a determined cracker or counterfeiter, but in the kind of environments I have mentioned, they would never get into the market. I would guess that educational establishments would also be a bit more of an "ethical customer" environment?

Just a quick thought................I haven't used one for years...........like when most music was on cassettes or still on vinyl