Pop up pro - disclaimer

Hi, writing to see if this plugin could be modified so that it could be displayed when a shortcode is called upon. The reason behind is I want to modify it so first time users will always see the popup and if user agree it would save a variable to a cookie and would not see the message again until cookie is cleared.

So I am hoping to say add something on the header.php if($_SESSION['active'] == "false") { do_shortcode('[popup1]'); }. Was wondering if this would work with this plugin?