Multiple per device RDS CALS are issued to the same VDI

Instructions

When the master image contains RDS Licensing HardwareID information that was generated from previous RDP usage, client devices connecting to clones of the master image might allocate multiple RDS licenses instead of just one license per client device.

The scenario goes like below.
 
•If Client1 has HWID **** and logs into the RDS, it will get license 1 
•Then Client 2 which also has HWID *** logs in and does not have license 1, so it's issued a new license, license 2 
•If Client 1 tries to log in again, the *** HWID is now associated with license 2, which Client 1 does not have, so Client 1 will get issued a new license, license 3 
•Now the *** HWID is associated with license 3 
•Every time that HWID logs in, no matter what machine it is, its license will be compared to what's in the database for HWID *** 
•That's where the problem comes in — machines are constantly getting new licenses, even when they aren't needed.
 
As a resolution to this issue, you will have to use a syspreped image which does not have MSLicensing Key information of the original machine hard coded to it and create VMs out from it.
 

Clients store their license under the key:

[HKEY_LOCAL_MACHINE\Software\Microsoft\MSLicensing]

The MSLicensing key contains two sub-keys used to store both unique client-specific information and any license certificates obtained from license servers.

HardwareID
Store

HardwareID stores a Random 20-byte identifier specific to the client machine and is generated automatically by Windows. This ID uniquely identifies the machine to the license server. When a client is allocated an RDS CAL from the license server, this HardwareID is recorded in the licensing database to associate the client with the CAL. This entry is made when clients are allocated both temporary CALs and permanent licenses.

Store is used to store the terminal services CAL allocated from the license server.  Entries are contained in sub key named License00x, where X is a numerical ID beginning with 0.  Each License00x entry contains a separate CAL.