To obtain the password for Respondus 4 Single-user, you can request a 30-day activation password at https://web.respondus.com/support/register-30-day-free-trial/ or purchase a permanent activation password at https://web.respondus.com/support/online-order-form/
In either case you will be asked to enter the Product ID that appears when you first installed and started the Respondus 4 software. The activation password will be e-mailed to you as soon as you submit the form.