Currently, logging in with your Google Account is only supported in the web app; for other services such as the iPad app, you can log in with your RTM username and password. (Even if you created your Remember The Milk account with your Google Account, you still have a username and password.)
If you forget your username or password, you can receive an email reminder here (for your username) and here (for your password).
Hope that helps!
Posted 3 years ago