Windows Server Technical Preview and Hyper-V Server Technical Preview Expiration Extension

Microsoft has released a solution that will allow you to continue using the Windows Server Technical Preview and Hyper-V Server Technical Preview from October 2014 without interruption until the next preview is available in May 2015. This solution is available as a free download from the Microsoft Download Center.

Download Instructions
If you would like to continue using the current build (Build 9841) of Windows Server and Hyper-V Server Technical Preview released in October 2014, please visit the Microsoft Download Center and follow the download instructions. This download will allow you to continue using the preview without interruption until the next preview is available in May.

Install Instructions
To install to continue using Windows Server Technical Preview and Hyper-V Server Technical Preview:

1. You can either run the installer from the Download Center website, or save the download package to a local computer or share. If you save the download package to a local computer or share, double-click the installer program, Windows6.4-KB3056022-x64.msu.
2. When you are prompted by the Windows Update Standalone Installer dialog box to install the update, click Yes.
3. Read and accept the license terms. Click I accept. Installation requires a few minutes to finish.
4. Reboot after installing. System may require up to 5 minutes to respond.

Notes: If you installed HyperV server from ISO, you cannot use the .msu package to patch it. You will need to use DISM.

Example:
dism /online /add-package /packagepath:Windows6.4-KB3056022-x64.cab

Source
Windows Server Blog