My Windows 8 Pro key obtained through DreamSpark Premium has an Edition ID as X18-15500. My friend's Windows 8 Pro key obtained through MSDN has an Edition ID as X18-15499. My cousin's Windows 8 Pro key purchased through the Microsoft Store has an Edition ID as X18-15501. I checked all the three different keys using The Ultimate PID Checker . These were common for all: Profile: NT 6.2 Edition Type: Professional Description: Win 8 RTM Professional Retail Key Type: Retail EULA: Retail Crypto ID: 1781 Now I want to know what is this Edition ID thing and why is it varying even though the SKU (Pro-Retail) is the same.