What before subscription API?
Before the launch of the subscription API, When the user tries to purchase the subscription product, they will redirect to the third party checkout which looks the same as Shopify checkout.
In the third-party checkout, The user can not apply the Shopify default discount code on third-party checkout.
What with subscription API (Native Checkout)?
In this App, We used Shopify subscription API. Here users can add subscription products to the cart with default Shopify checkout. No need for third-party checkout.
It overcomes the limitation of third-party checkout that is about Shopify default discount code. Here users can apply the Shopify default discount code on Shopify checkout cause it’s the default Shopify checkout.