This is a periodic promotion for those interested in online access to a large library of technical books. It seems to be a summer and Cyber-Monday event, but now's a good time to subscribe if you have been considering it in the past.
Offer through Aug 5th. (Has been extended in past sales, but I have no information if it will be this time.)
Edit: "for life" simply means that the renewal price will remain the same (unlike Adobe subscriptions