Your subscription will automatically renew at the rates stated on the subscription page when you sign up unless you cancel before the end of the billing period.
Grammarly will charge you monthly (or quarterly, annually) on the date you signed up. If your billing date is scheduled for a date that does not occur in a given month, you'll be billed on the last day of that month instead. Charges are billed at the beginning of your billing cycle and may take a few days after the billing date to appear on your account.
Note: If you are seeing charges on a new card that you haven't added to your Grammarly account, your financial institution has automatically updated this information as a courtesy. Financial institutions do this to ensure that accounts using recurring payments remain in good standing when a new card is issued. In some cases, your financial institution may also allow recurring charges to continue on an expired card. If you have any concerns about this process, please contact your financial institution.