Hello Mohamed, 

Once the billing has been processed successfully to the card on file, an email invoice will be sent to the master admin's email on file. Here's how to check if the email address is correct in QuickBooks Online.

1. Click on the Gear Icon.
2. Click on Manage Users.
3. Verify the Primary admin's email address is correct.
4. If it's correct, we still advise you to Edit the email by removing and re-entering the information.
5. Click on Save
    

There's also another way to get your subscription invoice copy in QuickBooks Online. 

1. Select the Gear icon, then select Account and settings.
2. Select the Billing and subscription tab.
3. In View payment history, you'll find your entire billing history

You can refer to this link to learn more about QuickBooks monthly subscription invoice.

Feel free to post a comment below if you need more help. I'll be around to assist you!