Most likely, you're trying to log in with a user account different from the one you associated with your license. When purchasing on our site, you entered a user ID that we have associated with your license. You can see this used ID in the email we sent you after the purchase or on the license in the Team Management site.
Please log in with the user ID on the license.
If the license has the wrong user assigned, you may be able to change it in the Team Management site: Can I Change My User ID for Supermetrics?