Webtrends Analytics 9 Adminstration Guide, November 2012
Visitor History requires that you use certain technology to collect visitor data. Because Visitor History leverages data collected using Webtrends query parameters, you must capture web activity data using the required Webtrends query parameters.
You can use Webtrends On Demand, Webtrends SmartSource Data Collector, or META tags on your site to capture data using Webtrends query parameters. You must also identify your visitors using a session tracking method other than IP address and user agent. As a best practice, you should identify visitors using first-party cookies, but you can also use authenticated user IDs.