What Yahoo! Search Subscriptions is?

Yahoo! Search Subscriptions is a search engine within Yahoo! that only searches subscription sites. It’s a little like a site search feature for several sites at once. When you arrive, you’re asked to click on any of the seven sites that Yahoo! can focus your search on such as:
Consumer Reports
Forrester Research

If you have a subscription to the sites that you’re searching, then you can proceed to those sites as you would from a typical SERP. If you don’t have a subscription to those publications, then you’ll end up on a page that says “this page only available to subscribers.”