It's already done. I've a Premier Membership and one of the services I get with it is exactly that information. On the Home page is near the op left corner is a link with my name and today's number of stories read out or what I can read - so it currently reads Ernest Bywater 0/100 - when I click on that it shows my Today's Access page with a list of all the stories I've read or opened today and a linked labelled History - click on that and you get a long list of stories going back for, in my case, 954 stories. The ones I've clicked on a page of the story since go back to June 2007 have the date I read the stories beside them - all 690 of them, the other ones have no date, but are ones where I've looked at the cover page with the chapter list but not accessed a page of the story itself. Confirmed by checking one of them out, and since it was written in 2013 and later in the list than 2007, it's clear the undated list is where I went to the story but not a page of the story - when I clicked on chapter one of a story in changed position and added a date.