This slides have been created using the Metropolis beamer theme (https://github.com/matze/mtheme) and therefore the same license apply to the theme files:
The theme itself is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. This means that if you change the theme and re-distribute it, you must retain the copyright notice header and license it under the same CC-BY-SA license. This does not affect the presentation that you create with the theme.