I was under the impression the Access Token changes every 3600 seconds but that the Refresh Token will stay constant. I have noticed that after each authentication both tokens change. What is the best way to track an amazon user: currently I am using the 'amazon user_id'. Does the refresh token only change upon a successful login? Does it expire over time?
noted in developer guide: [i]"When you are granted an access token, you may also receive a refresh token. A refresh token is valid for longer than an access token, and allows you to trade in the refresh token for a new access token and a new refresh token."[/i]