I'm asked on a pretty regular basis to share my mockups so here we go! There are eight different mockups in the ZIP file for you to download and put your screenshots on.
I'm not a fan of the rendered look that most mockups adopt so I always take my own natural looking ones.
These mockups are licensed under the Creative Commons Attribution-ShareAlike 4.0 International license.
To put it simply you are allowed to adapt and modify the photos. You are also allowed to use them commercially. But you must link/source back to the original source which is this post.