Here's the receipt (the asterisks are mine):
---------------
Transaction ID: 17LU7**********EDDHRTBUF7AKEDOF6A8A
Recipient: Nabble LLC
For: 100,000 credits for
http://forum.plumbr.euAmount: $25.00
Date: Mar 18, 2013
Payment method: Mastercard XXXX-XXXX-XXXX-****
Reference: 100,000 credits for
http://forum.plumbr.eu---------------
My accountant says that this lacks e.g. VAT info (even if it's not applicable, should be stated on the invoice) to count as proper proof of expense. We'll probably get by, but if you have an invoice template it would be good to get a proper invoice.
I'm not worried about the actual transaction or whether the credits were applied, it's just a paperwork question.