@iqgrande , you are not entirely wrong, as there are enough evidences on web to certify the ac address can be spoofed.  To over come that, you may want to consider using 1.) "vendor defined hostid": The FlexNet Publisher toolkit contains a sample C source file, examples\vendor_hostid\vendor_hostid.c, in which a fixed vendor-defined hostid is set up. In this section, you can use this file to run through a procedure for setting up a vendor-defined hostid. In a real situation, you would not use a fixed vendor-defined hostid, but would define and call a function that returns the hostid that you want to use. A vendor-defined hostid can be used on a SERVER or FEATURE line of a license file. OR 2.) Composite Hostid: A composite hostid combines hostids together to provide a more secure hostid. A composite hostid is a hashed 12-character hexadecimal value formed by combining the values of one or more simple hostid types. It can be used anywhere a simple hostid is used: on a SERVER line or feature definition line of a license file. Or if needed, then we can combine both the approaches in the same implementation, as mentioned here: https://community.flexera.com/t5/FlexNet-Publisher-Knowledge-Base/Steps-to-configure-a-combined-Vendor-Defined-HostID-and/ta-p/106651 Both these types are well defined in the FNP product documentation. I am attaching the latest version of documentation library for your reference. In case you have further queries, kindly do not hesitate you let us know through a support case or call. ... View more