To login, you will need the emailaddress you registered with during initial signup and a password. However, if you forgot your password, you can always reset it. There is no possibility to retrieve your password, but there’s a procedure so you can create a new password.
You need to visit the lost password-page. Then you fill in the emailaddress you used during initial registration and click ‘get new password’. An email will be send with a link. Click the link and choose your new password and save. You now can login again. Don’t forget to check your spamfolder if you don’t get the reset-mail.
Even if you don’t have an active membership, you still can reset your password.