My posts here are set to auto delete, because when I was a newbie someone said it's a good idea for privacy etc.
I just thought, though, when I die these unrehearsed words and messy thoughts will all disappear and no one will know if I was ever really here. And I kind of want to be remembered, if I'm to be honest!
There's another option : bookmark the posts you want to remain, and mark that option in the delete settings.