Why does an invoice ask for my license or a permit number?

Some trades must print numbers on the customer's copy — a plumbing or electrical license, an EPA 608 certificate, the permit for a water heater or a panel change. DeskOps asks only when your trade and the work call for them, and prints them on the invoice and the pay page. Business credentials are asked once: type one on any document and it is saved and filled in after that (on a computer you can also set them under Trade credentials; on a phone, Business profile holds your license number). A permit number is asked on the invoice, never the quote, because it doesn't exist until the work is approved, and it is asked per job: the last one is offered ("use it only if this job is on the same permit") so a follow-up visit is one tap. A plumbing quote asks only for the license and never blocks sending; the invoice still needs it.