Users are able to offer various options for purchasing goods and services at checkout through a subscription app. For example, customers can subscribe to a product delivery every month for a 10% discount, or every week for a 20% discount.
> Tip:
> To be eligible to use Shopify subscriptions, merchants must meet the [qualifying criteria](https://help.shopify.com/en/manual/products/purchase-options/subscriptions/setup#eligibility-requirements).
## How it works
To enable subscriptions, apps create [selling plan groups](/docs/api/liquid/objects/selling_plan_group), within which they create [selling plans](/docs/api/liquid/objects/selling_plan). These selling plans are linked to products and product variants. For example, a selling plan group called "Subscribe & Save" can offer selling plans that enable the customer to choose the delivery frequency and billing frequency separately. Merchants can offer multiple optional selling plans to customers, or specify a required selling plan for a product, such as "subscription-only" offers.
## Implementing subscriptions in a theme
You can use Liquid and JavaScript to integrate subscriptions into your theme. You should also review the UX guidelines for subscriptions to ensure a great user experience.
