Gravity Forms Access Subpages

gravity_forms_subpage_access.php

<?php 

/**
This code will go in your theme's functions.php file. Upon form submission,
it allows the user to access subpages. In this example, it's form ID 14 and the
registration page is 'product-tour' Once submitted, you may wish to redirect
the user to a page that has a TOC or something similar.
**/

// Indicate whether or not the product tour form (14) was submitted via Cookie
add_action( 'gform_after_submission_14', 'dknm_set_submitted_cookie', 10, 2 );
function dknm_set_submitted_cookie( $entry, $form ) {
	// Set a session cookie that the form was submitted
    setcookie( 'product_tour_registered', 'true' );
}

// Redirect if the form hasn't been submitted
add_action( 'template_redirect', 'dknm_protect_confirmation_page' );
function dknm_protect_confirmation_page() {
	global $post;
	$parent_id   = $post->post_parent;
	$post_parent_slug = get_post_field( 'post_name', $parent_id );
    if( ($post_parent_slug == 'product-tour') && ! isset( $_COOKIE['product_tour_registered'] ) ) {
        wp_redirect( home_url( '/lp/product-tour/' ) );
        exit();
    }
}

?>