You will not receive any additional charges after your plan has been cancelled. You may continue using your remaining credits through to their final date of validity.
Your Sendinblue account is still active and you can continue to consult your sent campaigns and export your data.
Please note that you will not automatically be downgraded to the free plan. You can sign up to a new plan any time you wish or opt for pre-paid credits. To subscribe to the free plan, contact our support team by creating a ticket from your account.