United, like many airlines, has long had special programs for high revenue customers. Their primary offering is Global Services. It was a relaunch of the airline’s old VIP program.
The status is invitation only, except that United 4 million milers are granted lifetime Global Services status. In general flying over 100,000 miles and spending at least 30 cents per mile on United tickets is required. The benefits you receive as a Global Services member are impressive.