Miro uses the system of recurring payments - your card is automatically charged at the end of every billing period. If you'd like to stop further renewals cancel your subscription in the settings. Here's how you can do that.
Set up by: account admin, billing admin
Go to the Account settings > Billing information > Overview and click Cancel subscription at the bottom of the page.
Cancelling subscription in the Billing settings
You will see a notification stating that your account will be active until the end of the billing period and that you won't be able to add new seats. If you have an unpaid invoice for additional licenses/Day Passes, your card will be charged immediately. Click Cancel subscription to confirm the cancellation.
Notification before cancelling a subscription
The account admins will receive an email notification What made you cancel your Miro subscription. When the billing period ends, your account will be locked. More information can be found here: What Happens When Subscription Expires.
You'll be able to re-activate your subscription before it's expired whenever you wish in the Overview tab of the Billing settings.