When the initial 60-day evaluation period nears its end, you can run the Slmgr.vbs script to reset the evaluation period. To do this, follow these steps.

1. Click Start, and then click Command Prompt.

2. Type slmgr.vbs -dli, and then press ENTER to check the current status of your evaluation period.

eval1

Error Description: 

0xC004FC07 The Software Licensing Service reported that the validity period has expired.

3. To reset the evaluation period, type slmgr.vbs –rearm or , slmgr.vbs /rearm and then press ENTER.

eval2

4. Restart the computer.

eval3_after2

eval3_after

This resets the evaluation period to 60 days.

*This tutorial using Windows Server 2012 Standard Edition

Source: Microsoft