  [stuff deleted]

You should be clear in your mind what your goal is. Two possible goals
are (1) maximizing you income from your program, and (2) minimizing
the number of illegal copies which get created. Accomplishing (2)
doesn't usually accomplish (1).

Most vendors have concluded that copy protection reduces the number of
normal legitimate sales by far more than it increase sales by virtue
of changing 'copiers' to 'purchasers', and hence merely reduces
revenue.  Most legitimate buyers nowadays (including me) have had bad
experiences with copy protected products (e.g., hard to make a
legitimate backup, incompatabilties when new system on system upgrade,
etc.), and they won't touch them with a ten foot pole.