Questions

The ones that actually get asked

Will a photographed document be accepted?: That is for the recipient to say. What helps is the whole sheet in frame, even light and a square angle.
Does a photo of a receipt count as proof?: That depends on who is approving it. Many accept a legible photograph and still ask you to keep the paper until the claim closes.
Thermal paper has faded — now what?: Nothing recovers a faded receipt, which is the argument for photographing on the day rather than at month end.
Should I crop the photos?: Leave a margin around the sheet. A crop that touches the edge of a stamp is the common reason a submission comes back.
Can I add a photo to a file I already made?: Merge the new page into the existing document — that is a separate tool and it also runs on your device.
When does the cost begin?: At the download. The first 7 days are an intro price, after which it is monthly or annual.