One account, and the businesses you put on it. Everything you add stays against the account rather than in the address bar, which is what the demo pages do.
What this does not have yet. There is no password reset, no email confirmation and no limit on how many times a password can be tried. Those are real gaps rather than things left off this page, so use a password manager and do not reuse a password you care about. Your email address is used to tell accounts apart and nothing else: nothing here can send you mail.