I remember learning that progress and updates in AppLab and GameLab are saved each time the Run button is pressed.
When are “versions” saved so that they appear in the version history?
From Dave (Code.org):
A new entry in the Version History is created only when the web page is closed and reopened (or reloaded). However, if you want to make a point of saving your project at a specific point in time, a better way is probably to Remix it.
In addition to being saved every time you press Run, App Lab and Game Lab projects are also saved once every 30 seconds while the app is not being run.