After downloading the plugin , simple copy the file
AutoSave.hxt into the HXT directory your A:M installation .
The plugin was originally designed as a working relief for me , and therefor raises far no claim to completeness or accuracy, however it is free .
Set "Enable AutoSave" to "ON" in the Plugin Properties -> AutoSave , thats all .
Here you can also change the time interval for for saving (in minutes in the range from 5 minutes to 1440 minutes) and the backup directory for this project .
The files are saved with increased numbers (*_0000.prj,*_0001.prj and so one) in a sub path from the backup path, the sub path is created from the actual date .