I have completed a C++ application.It is about 3.5 mb in size.

I need to create a demo version of this application,The application should not work after 30 days of installing and using it..

Is there something any software that allows you to create demo versions or what steps should i need to follow.(add codes,etc?)

any books,online materials that is available and i need to follow as an reference??

The first question you should ask yourself is: is it worth all the work to built in all those code to create a demo version?

What's your application about, what does it do?

You should also think about the following problem: If the trial/demo period has ended, the user could just set his computer's clock back in time :), you should also make this impossible to do ...

A simple approach might be to create a file that keeps track of first date and last date used. Then each time the program is opened, before progressing to the actual program itself you read the file. If current date is 31 day or more past first date, then don't let program run. If current date earlier than last date used, then don't let the program run. If the user is able to reengineer your code from an exe file, or figure out which file you are using to store the dates, so be it. I'm sure there are more sophisticated approaches that someone may chime in with.