Each entry is a date, a few lines, and an optional amount. Add a tag such as fuel, labour, or follow-up so you can find that kind of note later.
On your phone
It works with no signal. Entries stay on the device and sync when you are back online. Add it to your home screen and it opens as its own app.
A report when you need one
Pick a date range, see the total at the bottom, search the notes, and export Excel or PDF.