So you need to activate Office 2016 but don't have product key? Now, on this page, I’m going to show you how to activate Office 2016 without product key. I will take Microsoft Office Professional Plus 2016 in Windows 10 as an example. If you are using other versions of Office 2016 on other Windows, the ways shown below will also work.
If you have ever installed genuine Office 2016 with product key, but later lost or misplaced the product key, you can retrieve the product key by using a Product Key Finder tool. Then use the retrieved key to activate Office 2016.
Step 1: Download iSumsoft Product Key Finder tool and install it on your computer. After installation, launch this tool.
Step 2: Click on the Start Recovery button. Then this tool will immediately discover the product keys for all genuine software, including Office 2016 installed on your computer.
Step 3: When all product keys are displayed, click the Save to File button to save all the keys into a Notepad.
Step 4: Open your Office 2016 app, such as Word. When you are asked to enter the product key, enter it and then you can successfully activate your Office 2016.
If you get free Microsoft Office Professional 2016 installed without the product key, you still have to activate it before you can use it. Although there are many free ways (or tools) over the net which allows you to activate Office 2016 without the product key, we advise not to try any of them, because you cannot tell if the way (or tool) is harmful to your Windows PC, and to a degree, these free ways or tools actually cause infringement of Microsoft's rights. So the best way is to ask Microsoft for the product key or activation code.