Google Play Store sometimes has problems identifying payments and subscriptions when there are multiple accounts on the device.
Please ensure that there is only one Google account logged in to Google Play Store and relaunch Puffin to try again.
Please also check that the date and time on your device is correct.
You can go to Device Settings -> System -> Date & time -> enable "Use network-provided time", then restart your device and try again.
If this doesn't work, please reinstall Puffin from Google Play Store. It won't charge you again if you have purchased Puffin with your Google account before.
Please also ensure that your device is a Google Certified Android Device, and not being rooted or cracked.
If this issue still persists, please send the receipts to firstname.lastname@example.org .
You should find it in your mailbox with this title: Your Google Play Order Receipt from xxx.
If you can not find the receipt in your mailbox, please find Puffin Browser Pro in the following link and take a screenshot for us.