If you buy multiple keys it makes life easier - you know which payment is for which key and for which invoice. This way you have an unique identifier to match t

If you buy multiple keys it makes life easier - you know which payment is for which key and for which invoice. This way you have an unique identifier to match them. Without unique identifiers you have big problems. The payment description should at least mention the invoice number or order number. Undescriptive descriptions are terrible when you need to check / match something. Even a human will have problems not to mention autimatic systems. And automationg is something one could expect from decent systems. No manual checks. No ambiguity.