SAN FRANCISCO — Google Inc.'s memory is getting a little shorter. Just not short enough for some.

The company adjusted its policies last week to answer complaints that it never forgets what users have looked for.

Google said it would continue to collect and maintain an internal database of search-engine queries — as diverse as "digital camera" and "bomb making instructions" — tied to the specific addresses of the computers on which they were entered. But it will "anonymize" the data by stripping addresses from the records after 18 to 24 months. That's enough time, according to Google, to keep law enforcement officials happy and satisfy its quality-control needs.

"We think this change will strike the right balance," Google Deputy General Counsel Nicole Wong said.

Some privacy advocates wonder why search records should be kept for even 18 days. Microsoft Corp. and AOL, which run smaller search engines than industry leader Google, say they dump them almost immediately in the U.S.

"There is more that could be done," Kurt Opsahl, staff attorney with privacy group Electronic Frontier Foundation, said about Google's new policy. "It would be nice to see the window narrowed to a shorter time frame. The shorter the better."

The search-records issue hit the public consciousness last year when a federal judge denied Justice Department officials access to most of the millions of search queries they had demanded, arguing that doing so would violate people's privacy.

On Wednesday, Google said it had good reason to keep records of who searched for what: It can help the company better understand what people are seeking, how quickly they're finding it and what ads they're clicking on.

Search records also help Google recommend related search terms based on the country or region where the user is.

And in Europe, the law mandates that such records be preserved. Last year, the European Union ordered phone and Internet companies to retain traffic data tied to individual computer addresses for six to 24 months to help police investigate crimes. The EU left the exact time frame to each member nation to decide.

"At the same time," Google spokeswoman Victoria Grand said, "we wanted to implement a policy to show our users that we're concerned about their privacy by creating more transparencies and certainties about our data-retention practices."

Ari Schwartz, deputy director of the Center for Democracy and Technology, said Google appeared to be trying to reconcile several of its corporate missions that "sometimes run into each other."

"How do you search the world's information, not do evil and protect privacy?" he said. "To do all that they're going to have to make some hard decisions."

Yahoo, the No. 2 search engine, requires users to provide an e-mail address, birth date, gender and zip code when they sign up. The company said it uses that information to deliver conduct research and more relevant ads and services. When a law enforcement agency gets a subpoena for Yahoo customers' data, the company tells them so they can appeal, spokeswoman Kathryn Kelly said.

AOL, the No. 4 search engine behind Google, Yahoo and Microsoft, said it didn't link computer addresses to stored search results. Microsoft said it took a similar approach and faulted Google for not doing the same.