I'm not aware of such a program. If you saw one, maybe it's still in your "history list"?
There's "simpleinvoice", here on SourceForge... not in Nasm, but it might be interesting to look at.
Actually, I wrote a program similar to what you describe for my business (before I went out of business). In C, not Nasm (except for the last module, at which point I'd become distracted by asm). Existing programs are *far* more powerful than what I came up with. I'm pretty sure I'm smart enough to have figured out existing programs. I'm not sure I was smart enough to teach 'em to my secretary, so I wrote something that was, as far as possible, "just like we've always done it". Lame program, but it worked for my purposes.
If you can't find the program you have in mind, you *could* write yourself one. Much easier to find something that'll suit your needs. Some reason it has to be in Nasm?
Best,
Frank