Unfortunately, autoship is a feature that is only available to those who wish to build an e-commerce website on Shopify. This application is usually offered for an additional cost in the Shopify App Store. If you are working with Pet Store Websites, that cost is included in the monthly fee.
Interested in Shopify?? Read these FAQ's: https://endlessaisles.zendesk.com/hc/en-us/sections/360002084974-Shopify-Web-Integration