I need to know how can I make trial(demo) version of my program. Normally people use date & time to do it. But if user will change his system date I guess it will not work. I need to know the best way of making trial version which will work only 7 or 15 or 30 days. Is it possible to make something like that it(program) will kill all files after passing 30 days? Please help me.
store an integer (number of times opened) somewhere, for example in the registry and at every program startup check if that stored value is less than the total number of times the program is allowed to run. if the value is less, then increment it and run the program, or else inform the user that the trial is over, and exit.
if you want your program to run for a limited amount of time (15 days for example) then you could check the correct time from a time server using the internet, and store the first date and time the program was run, and then each time the program is made to run check the current date and time to see if the limit is not reached.