As stated, the policy hasn't changed since news less than 30 days old was made available free - with advertising - in September 2006. This was some of the discussion at the time:
QUOTE (bira @ Sep 7 2006, 08:35)

QUOTE
I think what I might suggest then is trimming down the 30 days 'free' to 14 days. People will come to autosport.com for the breaking news, but if they want to search the archives they should be members.
We weren't sure which direction to go on time limit. Whether it should be the last week or the last two weeks or the last month. Eventually, the mathematics won: we calculated how much page impressions we would like to get for advertising, and figured that a 30-day period would ensure us that kind of delivery. That said, let's see how it goes. We can always change that policy if we find that our calculations were too conservative!
However, there was a technical issue that meant, until recently, this wasn't always properly enforced on some of the more recent stories.
PLUS subscribers have access to the complete archive of over 80,000 stories stretching back over ten years - all completely ad-free - alongside exclusive features, high-resolution images, FORIX and much more.