Thanks for your interest in the Shortcodes App!
There's a 7-day free trial so you can test it out and see if you like it. We anticipate this is going to help store owners increase their sales by getting customers to the checkout page faster, and organising things in a much more fluid way.. and we also want to make sure we keep adding features, making it better, and giving great support -- so it's not totally free.
After the free trial period, a small monthly charge kicks in (this is just added onto your monthly Shopify bill, there's no other external payment setup).
You can see the cost for the App on the App page with the details & demo store over here: https://apps.shopify.com/shortcodes
If you have any other questions, feel free to contact us via firstname.lastname@example.org