Every image for the strips are taken from Unsplash and they are free-use regardless of credit (I usually always credit the images individually, but because they are only 10px high and because of the amount, I didn't bother). Here are a couple posts where I did do it individually because the heights were a bit bigger and recognizable Criterion & BuddyUP.
All of the SteemMonsters pngs are free to use according to @aggroed. The only limitation on the artwork is that you can't slap it on something and sell it (ie, toys, t-shirt etc etc).
You can use these dividers and not have to worry about a thing if you credit it back towards this post at the bottom of your post or something. The dividers themselves have a CC license on them now.
I'm glad you like them :)
Also... there are more!