CareerCup

i wonder if it is possible without any external storage. May be get the date

The first time the application executes it tries to check the date of from predefined location(some file or registry) for some object with encrypted name. If that object is not available then create new one(happens the first time). If the current date - start date > 30 must be the logic

I don't think there is a way to store state without using any memory. So, so if you application is part of a part of a package. You package can contain a file that stores a default size of a date, then during the execution of the program, write to that file, size the format of a date string is the same, you have effectively not used any extra space.

What about giving the first date as hard coded and compare it with the current date

How about the following pseudo code:

while (count-- > 30){
println ("Register Now!");
sleep seconds_in_a_day;
}
println ("Expired!");