KeePass is a program made to help you manage all your passwords. I’m sure you know that you never should use the same password at more than one account. And with all the accounts you’ll create you need to remember more and more passwords.
Add all your passwords to KeePass and protect them by one master password. When you need a password you don’t remember, just login to KeePass with your master password and then you can see your password in plain text. All passwords are stored in a encrypted database.