Valve updated the Steam Subscriber Agreement today, adding a few mundane things and one particularly interesting clause (via Gamasutra). Users are now required to “clearly indicate the source” when they use any Steam service to “promote or endorse a product, service or event” in exchange for money, free games, or another inventive.

This mirrors a change Valve made back in October for Steam Curators and is the latest attempt to bring new digital services in line with existing Federal Trade Commission regulations about properly disclosing potential conflicts of interest.

The FTC is an arm of the federal government that fights for consumer protection. Their rules have always applied to traditional media outlets, but this is the first time Steam has required its users to disclose conflicts of interest–possibly because of Steam’s Greenlight voting platform and user reviews.

Last month, Valve publicly asked developers to stop offering free games to users in exchange for votes on Greenlight, adding that it puts Valve in a “really uncomfortable position.” A similar issue cropped up in the YouTube community, prompting investigations by Kotaku among others.

“Generally speaking, if an advertiser or a marketer is paying someone to write favorable reviews, the reviewer needs to disclose that,” Mary Engle, associate director for Advertising Practices at the FTC, said to Gamasutra, “and that disclosure should be clear and conspicuous, and should be upfront and easy to see where the viewer won’t miss it.”

You can see the full user agreement, and compare the changes to the previous version here.