Ask HN: Should I enforce software licensing, and if so, how?

I am creating a commercial, installable software product, which I intend to launch next month.

I intend to license it at around $50/server. Most use cases need the software on multiple servers. Is there any way to encourage/enforce that customers who install 20 copies to pay for 20 copies instead of just one?

Is there a way of doing this without annoying the honest majority (minority?) of customers.

(I'm intending to build the customer's email address into the binary and help screen, to dissuade copying.)

What is current best practice re: licensing and enforcement?