On systems running in virtual environments, the license files and its features, are locked to the system(s) by the Unique Identifier (UID) calculated by the Uniface license software DLM.
A part of the calculation of the UID involves all the MAC addresses of the installed network cards on the system.
Changes to the amount of installed network cards as well as changes to the MAC addresses of network cards, will change the calculation of the UID, rendering any license feature based on the previous UID invalid.
Note: Please make sure that with request for new license files, the server configuration is finalized before running the dlminfo to calculate the final UID.
In Virtual Environments like VMWare and HyperV, it is possible for a dynamically assigned MAC address to change, upon reboot. Therefore, to ensure that the MAC address is static, we recommend setting the MAC address manually.
Here is a link to VMWare's knowledge base regarding the possibility of a MAC address changing: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=507
Changing the MAC address of a hosted virtual machine Details This article provides best practices and reasons for changing the MAC address of a hosted virtual machine. For an ESX/ESXi virtual machine, see "Setting a static MAC address for a virtual NIC (219)". For a Fusion virtual machine, see "Setting a MAC address for a virtual machine in VMware Fusion (1003479)". Solution When a virtual machine is powered on, the VMware application automatically assigns it a MAC address. The software guarantees that virtual machines are assigned unique MAC addresses within a given host system. However, the software does not guarantee that a given virtual machine is assigned the same MAC address every time it is powered on. In addition, the VMware application does its best, but cannot guarantee, to automatically assign unique MAC addresses for virtual machines running on multiple host systems. A conflict may arise, for example, if the virtual network adapters on different physical servers share the same subnet and are assigned the same MAC address.
Also addressed in this knowledge article are sections on "Avoiding MAC Address Changes" and "Manually Assigning a MAC Address".
Similar documentation can be found on Microsoft's site for changing MAC addresses when using Hyper-V.