Where can I get an invoice for the fees we are paying to the app?

It's good to see you here in the Community space. Let me guide you in locating the QuickBooks monthly subscription invoice in QuickBooks Online (QBO).

Let's access your billing history inside QBO for the monthly subscription invoices:

1. Sign in to your QBO account.
2. Go to the Settings icon and select Subscriptions and Billing.
3. Click on View Payment History.

I've attached screenshots for your reference:

For more information about billing history, please refer to this article: QuickBooks monthly subscription invoice.

For future reference, you can check out this article to learn how to change settings and turn on features in your QBO account: Edit company settings.

I'm always around to lend a hand if you need further assistance with getting a QuickBooks monthly subscription invoice. Have a great day.