Select the Auto Save... menu item from the File menu.
In the Auto Save dialog, tick the checkbox of the Enabled property.
Set the Frequency property. This is the number of intervals that will pass between auto saves.
If you want STAR-CCM+ to save one or more copies instead of overwriting the same simulation file, set the Max Autosaved Files property.
Select the Trigger Type. This specifies the type of solution step that should trigger the auto save operation. Unless this is for a transient analysis, the setting should remain at Iteration.
Click Close. STAR-CCM+ will automatically save during the next run at the intervals you specified.
To deactivate this feature, simply reopen the Auto Save dialog and clear the checkbox of the Enabled property.