A screenshot can show that someone searched a number in the past. It may not show who ran the search, whether the number belonged to this watch, or whether a report was added afterward.
Check what the image actually shows
Look for the service name, serial, date, and result. If any are cropped out, ask for the original report. Compare the serial in the image with the engraving on the physical watch and the sale documents.
Run a current search on the actual piece
If the seller agrees, verify the serial yourself close to the transaction. Save the new result and its date. A recent search still covers only the records the service checks and the information it had then.
Keep the screenshot as part of the file
Don't discard an older report; it may help establish what the seller represented. Keep it with the listing, invoice, and messages. If the old and new results differ, contact the provider rather than assuming one screenshot is fraudulent or definitive.
A screenshot is evidence of a past lookup, not a transferable guarantee. The watch and the serial need to match each time.
Run a Dated Check
Search the serial on the watch you're considering and save your own result.