If you want to present drafts of your story within a team or keep content exclusive, you can easily protect published Pageflows with a password. 

To protect a story click on "Publish" in the editor sidebar:

Editor sidebar with arrow pointing to the Publish button

Select whether you want to publish the story indefinitely or only until a certain time and activate the "Protect with Password" checkbox. Readers visiting your story will be prompted to enter the displayed user name and password. Pageflow suggests an auto-generated password. You can edit it freely if you want a password that is easier to remember.

Publish dialog with Protect with Password option checked, showing username and password fields

The dialog displayed to visitors of your story looks different depending on the browser:

Once you are ready to make your story publicly available, use the same workflow to publish it again - only this time make sure the "Protect with password" option is no longer checked. You can also password protect a story that already has been published without a password. Public access is then no longer possible.