Your most recent invoice has a status of 'Pending' and you're unsure what that means.
Heroku is automatically billed each month for the previous months usage. An invoice with the status of Pending has not been charged yet, but is scheduled to be charged soon. Our billing dates most often fall between the 6th and 12th day of the month, depending on weekends and holidays. We'll attempt to charge the card on file 4 times and notify you via email of any declined charges.
You can find more information on Pending invoices here.