Hello,
Are you using a virtual machine? Some virtual machines for some reason don't act exactly like physical machines, which causes the Net Express's license manager not to recognize the machine's fingerprint from time to time. The only solution is to make sure the virtual machine acts exactly like a physical machine.
If you're not using a virtual machine, I suggest reinstalling Net Express. Before starting the uninstallation, I suggest making sure the license shows "Full license" and revoking the license.
Regards,
