Multi-Factor Authentication is one of the best ways to ensure that nobody else will be able to sign in to your account, as it adds an extra layer of security; you cannot sign in without an additional code that is sent via SMS or displayed via an authorized app, such as Google Authenticator.
At this time, this feature isn't configurable to be required upon being invited to Punchh(if you would like to request this as a feature, be sure to bring it up with your Customer Success Manager). It is optional, and each Admin User within Punchh can opt-in after their first login by following the steps detailed, here:
How to: Configure Multi-Factor Authentication