Error Invalid license. Reason code = Missing DDL: [dbghelp.dll] Error: 0x7E.

dbghelp.dll is a file used for debugging purposes and it should usually be installed automatically with all other Windows files. There could be numerous reasons why the file is not present on your computer, it could be deleted, or quarantined by antivirus software, it could be corrupted or simply not part of your Windows version. 

At first I would recommend running a command prompt with administrator rights and performing the command: sfc /checknow

This will check your Windows system files for any issues and should the dbghelp.dll be part of your installtion, it should reinstall the file.

If this does not work, there's also an option to install the file manually by installing the Debugging Tools for Windows: http://msdn.microsoft.com/en-us/windows/hardware/gg463009.aspx

I'm not 100% sure which version would be the best here, but I supposed it's either the Standalone version or the SDK kit.

Don't forget to restart your computer once it's installed and then try running the beta again.