WooCommerce is an open source ecommerce plugin for WordPress.
WooCommerce’s Drip plugin connects your Drip account to your WooCommerce store, allowing you to track conversions, sales (events) and lifetime value. You can also add a checkbox to let customers subscribe to your Drip campaigns.
Set up this integration directly through WooCommerce.
For more instructions on customizing this integration, check out WooCommerce’s provided docs.