Use this overview to find the right Office 2021 instructions. First check the edition, platform and licence type in your order.
Microsoft support for Office 2021 ended on 13 October 2026. The duration of a licence is separate from its security update period.
1. Prepare your computer
Back up documents and Outlook data. Check your edition’s system requirements and remove conflicting older Office installations before starting the correct installer.
2. Retail: use your Microsoft account
Redeem an unused Retail key at setup.office.com with your own Microsoft account. For a previously redeemed licence, install from Services & subscriptions. Then sign in to Word with the same account.
3. Standard and Professional Plus
For volume licences, use the files and activation steps for the purchased edition. These keys are not redeemed on the Setup website like Retail keys. The detailed guides below point to the appropriate download and procedure.
4. Open your edition’s guide
Office Standard for Mac uses a separate guide; Windows installers and Retail steps do not apply to this edition. Office Standard · Mac
5. Check activation
In File → Account, check the product name and licence status. If an error appears, send your order number, edition and error message to MYKEYS24 support. Do not share your Microsoft password.
