A:AnswerMy wife wears it on her left index finger (same side as her wedding band, so her ring finger is already occupied. I believe the index finger is the finger the company most recommends for most accurate metrics.
A:AnswerYou can get basic info without one, but if you want all of the options and tracking that the ring offers (and let's face it, why pay that much for the ring if you aren't going to use what it is designed to do?) you need to pay for a membership.