Companies that have sales people or do direct response stuff will usually pay royalties. Bigger companies and B2B deals don’t usually… didn’t say never… just not usually. Like with other elements of getting paid, there is a level of trust here. Yes, you can have a contract, but in the end you just have to trust each other. I ask for regular reports and ask to have access to the books if there is ever a question. But, I’ve never looked at the books or tried to track it. My clients are honest and I trust them.