When first using the application the product key (license) has to be entered to activate Eva. You can find the key on your order confirmation.
By entering the key as admin (carry out as admin) the application can be used by everyone using the computer, otherwise only the user who has entered the key can use it.
You can deactivate the license at any time, so that you can activate it on another account or computer under Help >> Unregister. The license can only be deactivated by the user, who also has also activated it.