Before you enter a card, the checkout shows the subscription's terms: the monthly price, the first charge, that it renews on the same date every month until you cancel, how to cancel, and the date to cancel by to avoid the next charge.
The subscription starts only if you tick a separate box — unticked until you tick it — authorising the recurring charge. We keep that exact sentence, with the time and the IP address it was ticked from, on your subscription and your receipt.
You also tick the main agreement: the Subscriber Agreement (/legal/subscription-terms), the Priority Review Terms and the Refund & Cancellation Policy. We e-mail you the terms with your receipt, and your price is locked for as long as you stay subscribed.
Send a change request: billing mistakes our records prove are refunded automatically, and a person answers the rest within two business days.