In interactive mode (which is the default) the client will check if it has a valid authorization and, if not, will open for you a browser window so that you can log in with your credentials. After a successful login, the client will securely store an authorization token in your home folder, so that you will not need to log in for a certain amount of time. Depending on your configuration, this can vary from hours to days, but by default, a token obtained in this way will last 24 hours.