Flame Warden tracks which Midsummer Flames/Fires your character has honored/desecrated this year, displaying the year in the achievements UI.

If you've participated in the Midsummer Festival in the past, you cannot use achievements to determine which fires you've already visited this year; and that's where Flame Warden comes in: it records your interactions with the flames, and displays the year of the last visit to a particular fire in the achievements UI.

The (2008) text displayed in the screenshots is purely for illustrative purposes: Flame Warden has no way of knowing what you did last summer. Come next summer, however...