What it is
Dynamic Environment Manager captures user settings rather than user profiles. A roaming profile carries everything a person has ever touched; DEM carries only what an administrator has named: the Windows personalisation, and the settings of individual applications.
That difference shows up in the logon time, because there is far less to load.
How it works
The FlexEngine agent starts when someone signs in, imports the environment and personalisation settings, and then gets out of the way. Application settings are not part of that. They are loaded by DirectFlex at the moment the application is opened and written back when it is closed.
At logoff FlexEngine writes the remaining Windows personalisation back to the archive.
What it needs
No management server. It runs on files: SMB shares from a file server you already have, reachable on TCP 445, plus the agent on the desktops. Windows desktops, RDSH session hosts, fat clients and VDI all use the same mechanism, so it can also be used in an estate that is only partly virtual.
The two editions
There are two: Standard and Enterprise. What Standard covers was sold as Persona Management before it was folded in.
Two features are worth knowing by name whichever edition you land on. Self-Support lets a person restore their own application settings from a backup or reset them to default without opening a ticket, and the console can hide individual settings from that tool where that is not wanted. The Helpdesk Support Tool gives the service desk the same search plus the logs to investigate a profile problem.
What to watch
Before buying DEM for slow logons, find out how long a logon actually takes and where the time goes. The cause can also be an old login script.