Streaming viewers who pay by the month for Amazon Prime benefits, which include free shipping as well as entertainment offerings, now will pay $12.99 a month.

The new rate is 18% higher than the previous $10.99. The cost of a full-year Prime membership will remain $99 and the yearly rate for students also stays at $49.

Prime Video memberships, which offer access to streaming content, remain at $8.99 a month. The Prime Video option does not come with any of the other benefits of regular Prime, such as free or expedited shipping of goods purchased on Amazon,

The monthly Prime rate hike takes effect today, affecting any monthly renewals after February 18.

High churn rates have been a growing concern for many streaming services. Amazon’s decision to favor long-term subscribers over monthly ones gives it more of a hedge against subscribers dropping the service after their favorite show ends. That risk only will increase as the SVOD provider looks for epic, broad-appeal series amid a major executive leadership transition. Its forthcoming show Lord of the Rings is the first in this new line, as more niche fare such as One Mississippi and I Love Dick have been abandoned.

The pricing change also comes as Prime has reached a membership milestone. In a research note this month, Cowen analyst John Blackledge estimated that the service has 60 million U.S. members, a record level 20% higher than last year’s.

About 54% of U.S. households are now Prime subscribers, up from 18% in 2013, Blackledge said. “We expect rising Prime penetration in 2018 to continue as we have seen no clear indications of slowing demand for Prime,” he wrote.

Other estimates have been even higher than Blackledge’s. Amazon itself has not released official Prime membership data.