Retail keys are single-use. If your friend’s PC shows "Product Activated," the key is locked to their Microsoft account hardware hash.
Unlike , which is a cloud-based subscription service, Office 2019 is a "one-time purchase." This means you pay once for a perpetual license for a single computer. microsoft office 2019 product key list
Type cmd in the Windows search bar, right-click it, and select . Retail keys are single-use