If your payment went through successfully and the app does not show PRO features (this is easily tested since there will be "PRO" next to the Delta symbol) or you are shown the error code: 32459, here's a quick way to fix it:
Force close the app and re-open it.
Go into settings in the app (or press here to open Settings) and tap the "Restore Purchases" option.
In rare cases, if that doesn't work, please re-install the app, and use the same "Restore Purchases" button.
If the two steps above didn't help, it could be down a payment failure and PRO was not actually purchased. If you see funds have been taken from your account, this could just be a temporary hold that will be reversed (how long the funds will be held will depend on your bank). You can check if PRO was purchased or not by checking your subscriptions here: