Every book somebody pays for leaves here with a certificate number — the print-ready files, a printed copy, an Heirloom. Enter it and the register will tell you whether we issued it, what it was issued for, and when.
Free books are not in the register — that is what makes a number worth having. Every number we issue is signed, so one that does not check out was never written by us and no lookup is needed to say so. What the register cannot do is see the copy in your hands: it records what was made, not what is held. It holds only what is printed on the certificate, never a word of what is inside the book, and never what was paid.