Many sites list "free" or "top" product keys for activation, though these are often volume license keys that may not work for standard retail versions or could be deactivated by Microsoft later.
If you have lost or misplaced your product key and index, don't worry. Here are some steps to help you find them: index of ms office 2016 product key top
Q: Can I use a MS Office 2016 product key for multiple installations? A: It depends on the type of product key. Volume license keys can be used for multiple installations, while retail keys are for single installations. Many sites list "free" or "top" product keys
Once you have your key or your account is ready, follow these steps to activate: Open any Office application (Word, Excel, or PowerPoint). A: It depends on the type of product key
If you need Office 2016, here are your safe, legal options: