https://wccftech.com/google-has-reduced-play-store-subscription-fee-to-15-for-all-android-devs/

Google today has announced that it will only take a 15% cut on all the subscriptions from day one. Currently, the subscription fees only drop to 15% from 30% if the customers keep a subscription for12 straight months. This is similar to what Apple has been doing, but Google has said that “customer churn makes it challenging for subscription businesses to benefit from that reduced rate.”

Keeping that in mind, Google Play is reducing the service fee for all subscriptions from 30% to 15% "starting from day one." This removes the year-long requirement as well.