The product key is uniquely created according to your license requirements. Invalid product key messages occur most often for the following reasons:
Extra spaces or characters will be included during copying and pasting. You may also want to manually replace all “-” keys between characters with the “-” key on your keyboard. Whenever a license key is copied from an invoice, it copies a different character that looks the same as “-“.
You have an older version of the Office timeline installed, but are trying to use a newer key.
1.Open Word and find the Office Timeline tab.
2. Click the “Upgrade” button.
3. In “What do you want to do”, click “Activate.”
4. Open the Office Timeline invoice to ensure the license key is correct.
5. Copy the product key from the invoice or account, taking care not to include extra spaces or characters.
6. Paste the product key into the Activate Plus dialog.
7. Click “Activate“.
8. If the Office timeline displays a message stating “The entered product key is invalid,” continue with the following steps.
9. Close the word.
10. Uninstall the office timeline. In Windows, navigate to Control Panel > Programs and Features, select Office Timeline from the list, and click Cancel Installation.
11. Download and install the latest version of the Office Timeline from the update https://setup.office.com.
12. After reinstalling the Office Timeline, click the Office Timeline tab in Word and then click the Upgrade button.