When you choose one of the options to register your copy of Envision, the order form asks you to specify your User Number. This is unique number that is generated each time you install Envision on a computer. It can be found on the box that appears when you load an unregistered copy of the software, or by choosing About from the Help menu.
This number is needed in order for a matching unlock code to be generated for you when you register. Because Envision is offered as a free trial download, the registration form assumes you have downloaded the program and installed it for evaluation before registering.