You can use it for personal and commercial projects.
You can be downloaded and used all mockups for free for any of your projects - commercial or non-commercial purposes and change them as you like, do whatever you want. No permission needed.
Just do not try to resell them or create a competing or similar service using materials from this site - this is prohibited. Please post a link to this site if you send mockups to anyone or mention them on your resources and social networks, instead of uploading file to your server.
You do not have the rights to redistribute, resell, lease, license, sub-license or offer the file downloaded to any third party.