May I ask how can I check my product key of the Surface Pro 3 ? You probably know Windows 9 preview is coming very soon. I'm installing as soon as it's available to all consumers. But , how am I suppose to install back Windows 8.1 ? I downloaded the official installer from Microsoft's website but when i type in the product key ( My Computer > Properties > Scroll down to the last row ) , it said the product key does not contain any " 0 " letter ( The product key I saw on the My Computer's properties starts with the number " 0 " ) Any Idea anyone ?