Always link the key to your Microsoft account. If you lose the card, you can re-download the software from your account page forever.
Subscription software updates automatically, often moving buttons, changing menus, or altering workflows. Office 2019 is static. It will not receive feature updates. For users who value consistency—especially older family members or students who don't want their workflow disrupted mid-semester by an update—this stability is a feature, not a bug. office 2019 home and student
Skip Office 2019. Buy Office 2021 Home and Student for the extra two years of security updates. Or, if you are brave and want the latest features, subscribe to Microsoft 365. But if you find a dusty, unopened copy of Office 2019 for $50 or less—and you understand the risks—grab it. It will still run today, and for the next 12 months, it will serve you well. Always link the key to your Microsoft account