Free for use for any purpose. Under every picture there is a link from where you can download image with full resolution and quality.
https://th3r3v3nan7.deviantart.com/art/Fractals6-724665838
https://th3r3v3nan7.deviantart.com/art/Fractals7-724675682
These pictures are from my portfolio on deviantart and are absolutely free to use for any purpose.