An issue has been discovered that impacts FaceFX Studio Professional users on Windows 10. Major Windows 10 updates can invalidate the FaceFX license installed on a computer. Windows 10 updates can be installed automatically, and so the problem can occur behind the scenes even if FaceFX has not been used for a long time.
As always, it is recommended to set a reasonable expiration time to your license from the License Manager Administer Pool page. If you haven't used FaceFx in a while, then the license will have already been returned to the server and you are free to check it out again.
The issue will be fully resolved in FaceFX 2015.2, but for anyone using a prior version of FaceFX Studio Professional, a workaround exists to get your license back:
1) Install the updated License Manager here
2) Log in. Your license will be shown as being checked out, even though FaceFX Studio Professional does not recognize it.
3) Check the license back in (you may need to close FaceFX Studio Professional if it is open)
4) Check the license out.
The above steps will resolve the issue. It is possible that a future major update of Windows 10 will cause the issue again, in which case the steps will need to be repeated.