Apple has launched a new option for developers called "contingent pricing for subscriptions," enabling the sale of discounted secondary app subscriptions for existing subscribers.

Developers have a variety of ways to try and entice users to pay for in-app purchases or to subscribe to an app or service. Under a new promotional feature, developers can now offer discounts to people who are already on another subscription.

Announced on Friday on Apple's developer pages, contingent pricing for subscriptions is designed to attract and retain subscribers. Specifically, it lets developers offer a discounted subscription price to users so long as they're actively subscribed to a different subscription.

For developers, this can provide a number of promotional opportunities, such as offering a discounted subscription to a second set of features if a user already subscribes to a core version. If they have a suite of apps, the developer could offer subscriptions at a discount for other apps they make.

The discount isn't necessarily limited to just one developer, as it's possible for a discount to be offered to users of one company's app if they sign up to another developer's product.

One piece of small print is that the discounted subscription will only be reduced in price if the user is actively subscribed to the first subscription. If they discontinue the first subscription, the discounted subscription will return to the regular price.

Apple also adds that the discounts can be marketed to customers within an app, in planned App Store placements, and in "off-platform marketing channels."

Contingent pricing for subscriptions is currently being piloted, with Apple to onboard more developers in the "coming months." Apple is also asking interested developers to sign up for future notifications, with more details to be revealed in January.