Copy the custom link shown on the Redeem Link tab and use it as the Web Address (URL) for a button or a hyperlink in your email. This link contains special merge tags that will be replaced by real values once the email is sent to a subscriber.
Test the Redeem Link
The first thing that comes to mind is to send yourself a test email, but that won’t work. The reason why is that the redeem link contains merge tags that needs to be replaced by MailChimp. These merge tags are information about the subscriber and the list. This means that unless the email is sent to a subscriber of a list, it will not replace the merge tags in the redeem link with the correct values.
The quickest way is to use MailChimp's preview feature and enable live merge data. This replaces all the merge tags with the information from the current subscriber that you choose to preview. You can also switch between different subscribers to see the link change. When this feature is enabled you can click the redeem link to open the landing page where the unique code will be shown.