All you need is a pencil! I’ve done two of them and one loses memory after about a second, and the other about 2 seconds; it just depends on how thick/heavy of a line you draw. It doesn’t take much of a line at all, and if you’re not happy with it you can just erase the line and try it again. I did a little picture write-up about it here that was posted on reddit a while back: Astrolux A01 next mode memory removal - Album on Imgur