You want to reduce the amount of effort and annoyance for the user to perform an action :.
: If you give the user a card, it would better serve to something than else more than using your application (are going to keep another card in your wallet just for ONE application ?). Can't you use another card used for other purposes, credit card, student card, etc. ?
That said if you give the user a card, it is a personal one therefore it can be used as a logging device therefore no login nor password to remember or connection to the internet.
: Does your application uses internet ? I it does not, then do not use internet for logging.
If it does then the user is going to manage to have a connection while using the application. So no logging device required.
: Why has the user need to log in ? Is it useful for her or for you ? If it is just for you then forget about it.