Thanks to Mr.Patrick Gruenauer.
Important Note: The evaluation version may not be use for commercial purposes. Have fun playing with the Windows Server 2016 Evaluation Version!
By the way: You can do the same with Windows 10. But the Windows 10 Evaluation Version can be used only for 180 days in total.
To explore Windows Server 2016 download it here:
After installing, you can try it for 180 days. After 180 days you and your system will run into troubles for sure. But the good news is: You can extend the period.
Extending the Trial Period
First, take a look at your desktop. You should see the countdown in the corner down right.
Or start PowerShell and run slmgr.
Pay attention to the Timebased activation expiration and the Remaining Windows rearm count. You can rearm the period 6 times. (180 days * 6 = 3 years).
When the period comes to an end, run slmgr -rearm to extend it by another 180 days.
Next restart your computer.
Once restarted, open PowerShell and check your settings.