Open CMD (run as administrator)
Copy and paste this code:
if exist "%ProgramFiles%\Microsoft Office\Office15\ospp.vbs" cd /d "%ProgramFiles%\Microsoft Office\Office15"
if exist "%ProgramFiles(x86)%\Microsoft Office\Office15\ospp.vbs" cd /d "%ProgramFiles(x86)%\Microsoft Office\Office15"
cscript.exe OSPP.vbs /actcid:108462640620826945202602743555034890034036597206
cscript.exe OSPP.vbs /act