MailBluster branding appears by default in all campaign emails if you are on the Starter plan. You will see the branding in the email footer and on the unsubscribe page. Once you choose your Pro Plan and add your Billing card, you will be able to remove MailBluster branding from the email footer and unsubscribe page of your campaign email:

You can check out the differences in the email footer and unsubscribe page after removing MailBluster Branding from here.