In this blog post I show how to extend your trial period to three years. The evaluation version of Windows Server 2012 / 2016 is valid for 180 days and you can convert your trial version to retail.
To explore Windows Server 2016 download it here:
https://www.microsoft.com/en-us/evalcenter/evaluate-windows-server-2016/
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.
First, take a look at your desktop. You should see the countdown in the corner down right.
Or start PowerShell and run slmgr.
slmgr -dlv
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.
slmgr -rearm
Next restart your computer.
Restart-Computer
Once restarted, open PowerShell and check your settings.
slmgr -dli