He who pays the piper calls the tune. This phrase means that the person who pays a musician can decide what music he wants to hear. Applied to a broader scale this means the person who pays for any service has the right to say exactly what he wants. For example if me and a gang of friends were going out to dinner, and Bill wanted to go to McDonald's, Jim wanted to go to Woodys bar and grill, Steve wanted to go to Arbys Steakhouse, and I wanted to go to The Hard Rock Cafe, and I was paying, We would go to the Hard Rock Cafe. By the same token, if Jim were to pay, we would go to Woodys. That is what is meant by the phrase "He who pays the piper calls the tune."