When you attempt to activate a Redgate product with the wrong serial key, such as a SQL Compare serial key with a SQL Data Compare installer, this dialog box is displayed:
To ensure you are using the correct license information you can log in to the customer portal for an overview of all the products that you own, are an admin of, or have been invited to use along with corresponding download links.
You can also refer to the invoice you received when you purchased the license and click on the 'Need to download the Tools?' link at the bottom. This will give you the latest installer and will also check for updates when new versions are released.