We've added an ability to apply subscription-level discounts using promo codes. 

Promo codes can be generated in billing solutions that are integrated with Stigg (for example: Stripe), and therefore require such an integration to be in place.

Applying discounts to subscriptions using promo codes can achieved with only a few steps:

1. Create a coupon either from the Stigg console or directly in the in the billing solution that's integrated with Stigg.
2. Generate a promo code in the billing solution that's integrated with Stigg.
3. When customers enter the promo code in your in-app's self-service experience, validate it using the estimateSubscription and estimateSubscriptionUpdate methods of the Stigg SDK.
   1. If the coupon is valid - show the discounted price.
   2. If the coupon is not valid - a relevant error code will be returned by Stigg SDKs, which you could leverage to present to customers.
4. Provide the promo code to the provisionSubscription and updateSubscription methods of the Stigg SDK in order to apply the discount during subscription provisioning and update.

The new functionality is supported by the Stigg NodeJS SDK v0.62.3 or later.