Step 1: Go to and sign in (upper right-hand corner) with the Microsoft account that you used to buy Office. Step 2: After you sign in, select your name in the upper right-hand corner, and then select Order History. Step 3: Locate the Office one-time purchase or individual Office app, and then select Install Office to view your product key (this doesn't actually install Office). Step 4: Select Install Office again in the window where the product key appears. Step 5: On the Hi. Let's get your Office page, follow the prompts to sign in again and associate your product key with your Microsoft account.