I don't use this for keeping track of my creative thoughts but I use it for journaling. I use Rocketbook. It's a physical notebook but you can also scan it and

I don't use this for keeping track of my creative thoughts but I use it for journaling. I use Rocketbook. It's a physical notebook but you can also scan it and directly upload to your cloud storage of your choice. It has 36-pages which you can erase with just a wet paper towel.