To purchase the add-in visit Ajatix website http://www.ajatix.com/purchase.html. Upon the purchase, you will receive an e-mail with your personal registration information.
To register the Advanced CSS Drop Down Menu add-in select Help->Enter Key... in the top menu.
Enter your registration name and key exactly as they appear in the registration e-mail, including a company name, if present.
Click OK to complete the registration process.