Why does the License frequently become invalid after reboot?

Newer PCs especially some with UEFI present the network card as several
network interfaces to the software. This virtual network interfaces get
dynamically assigned MAC-Addresses, which may change after a reboot. Those
virtual interfaces are used for load balancing and fail over. Because
MAC-addresses are used to identify the PC for the License, the License
will become invalid after a reboot, when MAC-addresses are changed by
this.

To avoid this, disable features that introduce dynamic assigned
MAC-addresses or manually assign a fixed address for the virtual interfaces
if possible. Manually assigned MAC-addresses should have the locally
administered flag set. The first byte of these addresses ends
with 2, 6, A or E.

Alternatively you can use a dongle.