how can i make 1 week trial version create

Hope, you understood the logic,

I believe this can be achieved by the logic you implement,

1. You maintain the Time in the system "registry"values, where the application is installed.
2. you need admin rights to update registry, so while installing allow only admin rights user to install your application.
3. Always on application execution compare the registry value with the current date time.
4. Dispose object and stop execution if the trial days are exceeded.

Note: This way can be hacked, where many Trail version are used by changing system date, so you can maintain latest system date in other registry variable.