Pandora will remove its 40-hour-per-month limit on free mobile listening Sept. 1. The company says it was able to make the change due to progress with its mobile advertising. "We're pleased to once again maximize free listening for everyone on Pandora," says founder Tim Westergren. "The more than 70 million listeners that tune in every month will now have more time to hear the music they love, and thousands of working artists will reach more fans." The limit was introduced in March (CAT 2/28) to manage rapidly increasing royalty costs.