I was automatically billed for 1 month after my free trial period ended. I'd like to have a refund

According to the agreement that you signed when accepting the trial offer, it's your responsibility to cancel the trial before the renewal date. If there’s no cancellation on record, the paid plan is automatically activated. Since we absorb various costs when offering the free trial, we are unable to cover expenses for the following months. If you don't want to be charged next month, just cancel the subscription auto renewal right now. Your plan remains active within the paid period and is cancelled upon expiration.

Our complete policies can be found here.

However, refunds for subscriptions activated via mobile apps can only be made in accordance with the terms of Google Play or the App Store and only through the respective stores.