Each time you perform an Advanced search, the criteria are stored as a 'recent search' so that you can run the same search again, without having to re-populate the search fields.
You can view a stored search by clicking on the numbered hyperlink that represents that search in the ‘View your recent searches’ field at the bottom of the ‘Advanced search’ page.
When you select one of these hyperlinks, the website populates the fields of the ‘Advanced search’ page with the settings that you had when you ran that search. Simply select the ‘Go’ button to repeat the search as it is, or change the settings in the fields first if you want to amend the search.
Your searches are stored as a 'cookie' on your computer, which means that they will be available each time you access the website.