Businesses simply need to get the proper invoices. By all means do enough work to make that visible and easily obtainable for them if you want to get any money.

Still, the money from what you call "useless" licenses is minimal compared to the one that the businesses are ready to pay if they don't have any other alternative but to pay. Business are the systems that are designed to make profit. If they don't have to pay, they typically won't.