It was used during installation to unlock the software. For (versions like Home & Student, Home & Business, Professional Plus), the key determined which edition and features were accessible. Unlike earlier versions (e.g., Office 2010), Office 2013 introduced product keyless installation for volume license customers via Key Management Service (KMS) or Multiple Activation Key (MAK), but retail and most small-business users still entered a key manually.
By 2013, the product key model was already showing its age. Users lost keys, found them cumbersome, and turned to cracks or KMS emulators. Microsoft’s long-term strategy—fully realized by Office 2016 and Microsoft 365—was to move toward: microsoft 2013 product key
Microsoft Office 2013 remains a widely used productivity suite for individuals and businesses who prefer perpetual software licenses over subscription models. Activating this software requires a valid, 25-character product key. It was used during installation to unlock the software