Checkout Upsell is available for all stores on the Recharge Pro plan and using Shopify Plus. This feature encourages your customers to convert one-time purchases to subscriptions at checkout in one easy step.

Checkout Upsell is a Subscription Experience that displays a “Subscribe and save” link during checkout that customers can click to convert their one-time order to a recurring subscription. If a customer changes their mind after clicking the link, they can easily return to their original one-time order. 

You can read more about this feature on the Upsell subscriptions at checkout Help Center guide.