User Configuration > Administrative Templates > Microsoft Project 2016 > Project Options > Save > Auto Save Options
User
HKCU\software\policies\microsoft\office\16.0\ms project\options\save
Specifies whether Project should prompt the user before saving their project as a result of the Auto Save function. If you enable this setting, users will be prompted before their project is automatically saved. If you disable or do not configure this setting, the user's default setting is used.