Personally I've never understood the need some have for keeping chat histories. So this isn't a feature I'll use, but am sure others will.
And remember, Signal is a nonprofit. If you use it, and if you can, you should be donating.
replies(3):
And remember, Signal is a nonprofit. If you use it, and if you can, you should be donating.
Just save the pictures in the camera roll and important messages in your notes app of choice.