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In [DPM Administrator Console], on the navigation bar, click [Management], and then click the [Agents] tab. Now you’ll notice that panel scores have all set to 0 as nothing has been installed yet.

In the [Actions] pane, click [Update DPM Licenses].

Fundamental rule is that you must use a single license for each computer protected by the DPM.
There are three type of Agent licenses available in DPM.

Client Agent License: This applies per protected client computer basis. This License entitles you to protect data in the client computers operated with Windows XP & Windows Vista OS.

Standard Agent [...]