Capture One CH automatically saves your work as you image.

It is a good idea however, to back up your work at the end of the day on a separate drive, so it exists on two locations. Keep a good record of where you save your work, especially if you are working on different versions/sessions at a time.

If the project you are working on if significant, it is better to create separate sessions to avoid handling too big of files. See Creating a new session.