Yes, the cheat is: aging off - you have to do it each time you play and with each individual household. If you don't want to cheat, you can use the Elixir of Life aspiration reward.
With University, you can lure a sim to a cowplant and 'drink' them for extended life and with FreeTime you can wish for a longer life via the genie. These methods are obviously more tedious, though, so I prefer the cheat. ;)