Don't worry! Let's take a look and see what happened.

A) I've already paid and received a notice that the card was processed, as well as a receipt from Apple, however I never received the item I purchased:

Please go to the Settings page on the Plant Nanny² main menu. Then tap Restore Purchases. Look to see whether you have now received the item you purchased. If you still have not, please go to the Settings page on the Plant Nanny² main menu and tap FAQ to contact us. Be sure to attach your Apple receipt with your message to allow us to better assist you!

Note: Please be sure to include your FDID when reporting the issue. For convenience, you can go to Settings > Tap your profile picture > long press on your FDID first to copy your FDID. If you haven't already linked with a social media account, please do so. This will allow us to view the purchase in question and take steps to resolve your issue. If you haven't registered previously and do not wish to register your account, we ask that you instead request a refund for your purchase. For information on how to request a refund, please see here.

B) I've already paid and received a notice that the card was processed, however I haven't received a receipt from Apple or the item I purchased:

Please go to your phone's settings and tap your name, then tap iTunes & App store > Apple ID > View Apple ID and tap Purchase History. Look to see whether or not the purchase in question is on the list. If it is not there, or it is there but you have still not received a receipt and the purchased item after more than 24 hours since the purchase date, please use this page to contact Apple Customer Service.

If you are an Android user please see this tutorial.