Re: 30 days trial immune to set clock back in time?

To give a clear analogy:

Suppose someone is taking a test with a one-hour time limit. This time
limit is kept in a nice, visible timer in the room. What the OP was
asking was "How do I ensure that the test taker does not add one hour to
the timer halfway through the test?" Is the test taker doing something
wrong by adding an extra hour? Yes. Is placing a monitor in the room to
stop the test taker from manipulating the timer wronging the test taker?
No. Would it be fair to have the test taker who attempts to manipulate
the timer fail the test right then and there? Yes.

So, is attempting to use a service for longer than the user agreed to
use it wrong? Yes. Is attempting to detect an attempt to manipulate the
agreed-upon timer wronging the user? No. Would it be fair that the
penalty for the attempted manipulation would result in immediate
lock-down of the program? Yes.

Another way to look at it is like a library. I can check out books for
free, but I only have them for a limited time. If I attempt to hold the
book for more than I agreed to check it out, the library has every right
to penalize me. If I want the book for longer, I have to buy it. By your
argument, the library should just shrug its shoulders if I keep the book
for more than X weeks.