Pandora will place a 40 hour listening cap on its free mobile music streaming service this week.
Pandora users who reach the new limit on their mobiles can pay 99 cents to lift the cap for the rest of the month, or subscribe to Pandora One for $36 per year for unlimited streaming with no adverts.
Those who will be affected by the changes are in the minority. according to Pandora founder Tim Westergren who made the changes because their streaming royalty rates are increasing.
"The average listener spends approximately 20 hours listening to Pandora across all devices in any given month," said Westergren on the Pandora blog.
"Pandora's per-track royalty rates have increased more than 25% over the last 3 years, including 9% in 2013 alone and are scheduled to increase an additional 16% over the next two years. After a close look at our overall listening, a 40-hour-per-month mobile listening limit allows us to manage these escalating costs with minimal listener disruption."
Pandora has been lobbying Congress to reduce the royalty rates it has to pay to artists. Meanwhile, artists are angry that they may receive even less income from streaming, and many feel the current rates are already too low.
In December, five of the world's leading songwriters led a protest on Capitol Hill to demand a fairer share of Pandora's profits, but the streaming company argues that it can't sustain itself at the current rates.