I have decided to go ahead and turn on aging. I have not yet played that way. However... My main Sim I want to NOT age up. Without cheats, what are my options? I know I can use the potion of youth. ...
You can have your sim work in the science career. they will eventually be able to make the age away potion. then the cloning machine...and then they will be able to make enough age away for the whole family. you have to make the cloning machine before your sim quits the career though, because the chemistry station does not work if they are not a scientist.