In a blog post, the online ad giant said its cookies would soon be set to expire after two years, rather than in 2038 – its current time limit.
Its definition of active users, however, means that cookies will be automatically renewed unless a surfer avoids returning to Google during the entire two year period.
Google has been coming under pressure over the way it stores users’ search queries – an issue highlighted by the AOL search data fiasco last year. In March, it announced it would “anonymize” its search server logs after 18 months in a bid to improve security.
Global privacy counsel Peter Fleischer said it had listened to feedback from users before “taking a closer look at the question of cookie privacy”.
"We've concluded that it would be a good thing for privacy to significantly shorten the lifetime of our cookies — as long as we could find a way to do so without artificially forcing users to re-enter their basic preferences at arbitrary points in time."
Fleischer said the original limit was set so far in the future because its primary purpose was to preserve this information on users - for example, whether they would like results in English.
He said users would still be able to control their cookies via their browsers – although research by Benjamin Edelman last year found Google cookies often escape detection by anti-spyware software.