For physical product purchases, your product serial number can be found on either the back of your product quick start guide/manual or on your product CD sleeve.

For download product purchases, your product serial number is included in the confirmation email you received in response to your order, or it can be found on the Extensis website on your My Account page.

If you have already activated (personalized) your product, with its serial number, you can find the serial number again by opening the application and selecting "About (name of product)".