Hi Friend, I am Sofia Carter. If you have purchased a new Microsoft Office product key card, you can visit office.com/setup to activate it. If you had received a product key when you bought Office via any online store, then also you can visit the website mentioned above. From there, you can adhere to the prompts you see on the screen for activating your product key. Remember that it is only a one-time procedure wherein your new product key is added to your Microsoft account.