include php file if page_id matches

Make sure to add it to a hook that fires at or after ‘wp’ ;

Example:

add_action( 'wp', 'your_function_name');

function your_function_name(){
    global $post;

$your_page_id = get_option('your_option_name');

    if( $post->ID == $your_page_id ):
//your include 
endif;
}