The author of the article's instructions did not work for me, so I looked it up and found these instructions from Apple Support:
See your purchase history on your iPhone, iPad, or iPod touch
"Open the Settings app.
Tap your name, then tap iTunes & App Store.
Tap your Apple ID, then tap View Apple ID. You might be asked to sign in.
Scroll to Purchase History and tap it. If you want to see purchases that you made more than 90 days prior, tap Last 90 Days, then select a date range.
Find the item, then tap Total Billed.
From here, you can do these things:
To request a refund or report a problem with the item, tap the item, then tap "Report a Problem" and describe your issue.
To see the date when you bought the item and the device you used to buy it, tap the item.
To send yourself a new email receipt, tap Resend. You can’t send a receipt for a free item."
I chose the option to send myself a receipt, and that worked.