If you are trying to activate the FLS key on the virtual machine but on the Status page of the license server web-interface see "Server Down" messages in the ISV Servers table in the line related to "agisoft", like shown below:

and the following lines are displayed in rlm log:

08/17 07:24 (rlm) The ISV server is running on the wrong host.
08/17 07:24 (rlm)
08/17 07:24 (rlm) This can happen if:
08/17 07:24 (rlm)  The hostid of this machine doesn't match any license file
08/17 07:24 (rlm)  - or -
08/17 07:24 (rlm)  You are attempting to run the server on a virtual machine

It means that you require an additional activation key that would enable FLS running on the virtual machine. 

Floating license server can be activated on one machine (dedicated computer or a virtual machine).  To activate FLS on Virtual machine you need two key-codes: one is FLS activation key provided upon purchase and the second one is the key to enable FLS activation on Virtual machine (additionally provided upon request).

To get this additional key (VM-enable), please contact the reseller whom the floating license has been purchased from or sales@agisoft.com directly and specify the order number and the related FLS key sequence that you would like to be activated on the virtual machine.