All Udemy courses come with a Udemy certificate of completion. When all lectures have been completed, a gold or green trophy will appear, signifying that the certificate of completion is ready for download. Click on the trophy to view the certificate.

For more info go here: https://support.udemy.com/hc/en-us/articles/229603868-Certificate-of-Completion 

If by any chance you are unable to download the certificate even after following the above steps, please feel free to write to me and I will try my best to help you with it. Good luck and Happy Learning.