Hey There, I am Dayna Martin. When you download and install the latest version of Microsoft Office Setup on your Windows desktop, then to start its product you need to activate the software. To activate it, product key containing 15-digit is definitely required. You can get it from the retailer, behind the disk drive, or by accessing the site www.office.com/setup. After entering that activation key into the desired field you can frequently start using any of the Microsoft Office Productivity program for your documentation work. We are providing helpline number through you can also direct contact us for instant help. We are happy to assist you!