In March 2015 Google announced a change in its AdWords policy, under the Unsupported Content section. As part of the change, Google will prohibit promoting free desktop softwarethrough Google AdWords unless the ad explicitly names the promoted software's name andleads to a landing page on the site designated as the software's primary distribution source.
The new change is part of Google's continuing “front” against advertisers who use Google AdWords to promote free software using misleading techniques. According to the announcement, advertisers will be required to comply with the new change around late April 2015. By that time, the new policy will be published at Google's legal requirements & serving limitations page, which explains that: "in addition to the advertising policies and other legal requirements that advertisers must comply with, we occasionally must also ban or limit certain kinds of businesses from advertising with us, even if certain individual businesses appear to comply with our other policies... we occasionally identify products or services that are prone to abuse by untrustworthy actors. If we feel that certain kinds of businesses with these characteristics pose an unreasonable risk to user safety or user experience, then we may take a more conservative position and stop related ads from running".