It's easy to configure how and when users can run Test Drives. Whether a customer is new or existing, you can control who can register to run a Test Drive, whether a user has to be approved first, and how many Test Drives a single user can run.
By default, all users that register must be approved before they can run a Test Drive. This setting can be overridden in the Account/Options section. Domains or email addresses in the green list are automatically approved for new accounts, and can run an unlimited number of test drives. Domains or email addresses in the red list will not be allowed to register or run test drives. Domains or email addresses must be separated by commas.
By selecting the box "Automatically approve new customers to initiate Test Drives," customers can run test drives without first being approved by an administrator. They will be limited to launching test drives by the launch limit specified in the test drive itself.
Selecting “Require e-mail validation” will require a user to click a link in an email that is sent to them before they can access a test drive
Customers by default can only run a single Test Drive at a time, unless they are in the green list. This can be overridden on a per customer basis by navigating to Customer -> Edit and selecting Allow Concurrent Test Drive Instances. Customers can also be allowed to launch unlimited Instances of a single Test Drive by selecting "Unlimited Test Drive Instances" in this menu
For information on configuring the Test Drive widget, please see this article.