Extrait de Technet
If the size of the profile cache exceeds the configured size, Remote Desktop Services deletes the least recently used profiles until the overall cache goes below the quota.
You can configure the maximum size of the roaming user profile cache on an RD Session Host server by applying the Limit the size of the entire roaming user profile cache Group Policy setting. The Group Policy setting is located in Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Profiles. If you enable this policy setting, you must specify a monitoring interval (in minutes) and a maximum size (in gigabytes) for the entire roaming user profile cache. The monitoring interval determines how often the size of the roaming user profile cache is checked.