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I have developed a result processing software, I now want to make it demo for trial period of 3 days. How can I write code to make it trial? please help me...

[edit] spelling [/edit]
Updated 22-Apr-12 12:11pm

With respect, the fact that you're asking such a question in a public forum indicates that _you_ can't write one that will be worth the code it's trying to protect.

You know how some people do cross-words for fun? Yet others do Sudoku puzzles for fun. Other individuals create 'trial-versions' simply for the sole purpose of providing a challenge.

Search for "crackme" in google and prepare for a lot of results. (about 8 million)

My advice to you would be to make use of a commercial (or free) application protecting software. Armadillo, ASProtect, EnigmaProtector all spring to mind.

I really, really, really don't want to be discouraging - but I feel the need to say these things to avoid you having unrealistic expectations. Also, .NET applications are typically very easy to break-in to. - Last time I tried, it was about an hour's worth of work to make a key-generator for a £99 cad program.

Typically, people that create 'roll-your-own' protection schemes fall into the same traps and make the same mistakes. Commercial protectors are exponentially better than anything you, I and all the other people that have answered could create ourselves.

Options 3 and 4 of Sandeep's answer are generally considered the best, though with time even these are cracked. Assasin's Creed used option 3 and was still broken fairly quickly.

Best of luck! :)
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Gopal Rakhal 24-Apr-12 12:21pm    
thanks, but i need just for user not for programmer...
There are different ways to achieve this:

1) encrypted license files that contains the expiry dates etc.
2) encrypted license keys held in the registry
3) challenge/response mechanism which require an internet connection
4) probably others.......

Try: License Key Generation[^] or: How can I create a Product Key for my C# App[^] or: c# Licensing[^]
Couple of them are in C# which can be seen to start on Vb.NET

This one too: Application Trial Maker[^]
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Go through the following tutorial which will help you-
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After reading your question, i thought this is a good thing to write. so i wrote a small class for making a trail version. it is written in very less time and has lot of scope for improvement but it wil give you a basic idea about how to accomplish this. find it here:
Implementing a Rudimentary Count Based Trail Version Plugin for Windows Applications.[^]
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