On Jun 5, 6:19 am, William Foster <nos...@devdex. comwrote:
Good evening all,
I have written a single file program in Microsoft Visual Basic 2008
Express Edition that I need to build with a Trial Period.
I have built in a simple check the date procedure; but anyone can get
around that. Does anyone know how I can write back to the program file
so that the software self destructs or becomes unusable after a
particular date is reached even if the person sets the date back a month
or two? I thought about creating a second file that stores the date but
then if they delete that it will just think it is a new computer it has
never been used on before.
Any help you may be able to provide would be greatly appreciated.
Yours sincerely,
William Foster
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It should also be mentioned that whatever steps you take to implement
this trial period can be easily found out by using a program like
Reflector. With that said, you should either use an obfuscation
program to make the source harder to read, or write that part of the
code with a language that cannot be easily disassembled such as C++ or
even VB Classic.
Some questions you really need to ask yourself are:
How important is what you are trying to protect?
How much are you willing to pay (in time, money and effort) to
implement this behavior?
What are the chances people are going to try and bypass your
implementations ?
Those all come down to this last one, which is normally the decision
maker:
Is the cost (in time, money and effort) going to be more than the
potential lose in income from people bypassing the trial period?
One other option is to offer two versions of your application, one for
trial and one for retail. In the trial version leave out functionality
that would make upgrading worthwhile, or add in features that are
removed in the retail version (advertisements , watermarks on printed
documents, a splash screen that lists the upgrade benefits, etc). I
realize that these (especially the former) might not be possible to
implement in all applications, but when you can I believe the return
on investment is much greater than trying to implement the trial
period functionality.
Thanks,
Seth Rowe [MVP]