The Plezmo app automatically saves your code as you work on your project, so that you don't have to remember to do so manually. We do recommend that you backup your projects, just in case something goes wrong. To backup a project, go to the Projects section. Click on the 3-dots next to the Project that you wish to backup:
Click on Export to Device to save on your desktop.
You can also use this technique to share your work with your friends or to open it on a new device.
To import your project on a new device see this article.