Struggle to understand orm autoManageSession

I am having a hard time understanding the exact consequences of setting   autoManageSession

to false.

The docs say that if it is set to false, then "the application is responsible for managing cleanup, cleanup, or session close."

So what are the practical implications for this? Does my ORM code cover everything for me? What do I need to do manually so that CF will automatically do for me if this option were enabled?