It sounds like Mini Metro’s license verification thinks you don’t have a valid receipt for the game. Including this check is required for Mini Metro’s inclusion in the Play Pass subscription. It checks every month or so to make sure you either have a valid receipt from purchasing Mini Metro, or a current subscription to Play Pass.
We’re still trying to nail down how exactly to prevent these rare false positives from occurring. Could you please try force-closing Mini Metro, disconnecting and reconnecting to the internet, and starting Mini Metro again? If that also fails to work, could you try restarting your phone first?
If neither of those work and you would like a refund, please send me the Google Play receipt id. It can be found on the email you would have received from Google when you purchased the game, and looks something like GPA.XXXX-YYYY-ZZZZ-WWWWW. If you don’t have the email, you can look up your order history online.