Easy check out with Google customer reviews app

Shopify Plus Plan stores have their checkout on their own domain. This app provides a code to be inserted in the checkout for just a one-time fee.
On Non-plus Shopify stores, checkout is on Shopify.com and Opt-in Module does not work on it. So, this app provides additional order confirmation page that is on store's domain and fulfills the technical requirement of Google Customer reviews program.