I have always had '
colornote' on my phones. It's an app that mimics post its. you can swipe them off when you're done.... .but it keeps them if you swipe the opposite way, they remain.
It has a checklist or text option. you can also choose the note color, and organize that way... archives, lots of customization, transparency, search, etc. and it's free.
for things I want to have forever, and maybe share, I use google docs.