You can access your licence details and invoices on the www.pscs.co.uk website. To log into the website click the Login button at the top right of the website.
You will log in using the email address you specified linked to your account (usually the email address you used when placing your order) and your password. The password is initially randomly generated and emailed to you with your invoice(s). If you have not received the password, or have forgotten it, you can click on the 'Forgotten Details' link on the login page to have it resent to you.
Note that accounts are created when your first purchase is invoiced, and invoices are added manually to the system, so if you have recently placed your first order, you will have to wait until your purchase is invoiced before you will be able to log into the website.