Visit bookbeat.com and log in to your account. Once logged in, go to Subscription and then click on the button "Reactive my account" and your account is reactivated. You might need to update your paymentdetails again.
If your payment details are no longer valid, you might have to update them before you can reactivate your subscription. To do so, click on "Payment Method" and then "change". Enter your new information and press "Save." Finally, press "Activate subscription" again.