Repeated activation prompts usually mean Office has not fully completed activation or Windows itself is not properly activated, which can interfere with Microsoft 365/Office licensing.
For Microsoft 365/Office on a home PC, common causes include:
- Windows or time settings issues
- Activation can fail if Windows activation or system time/time zone is incorrect.
- In a documented case, the time‑zone function in Windows interfered with Office product activation and caused repeated prompts until it was fixed.
- Verify in Windows Settings that date, time, and time zone are correct and that Windows is activated.
- Licensing/installation state problems
- If Office thinks it is in a trial or OEM state, or if there are leftover OEM keys, it can keep prompting even after signing in.
- On some new PCs, OEM Office registry entries can cause repeated Microsoft 365 activation prompts. The documented fix is to remove specific OEM registry keys after backing them up:
- Close all Office apps and the activation window.
- Open Run, type
regedit, press Enter, and allow Registry Editor to open.
- Navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\16.0\Common\OEM
Export this key (File > Export) to back it up, then delete it (Edit > Delete).
- Repeat for:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\16.0\Common\OEM
- Close Registry Editor and start an Office app again, then sign in/activate when prompted.
Editing the registry is risky; deleting the wrong keys can cause system or Office issues, so a backup export before deletion is essential.
If prompts continue after confirming Windows activation, fixing time/time zone, and cleaning OEM Office keys, contact Microsoft support for a deeper activation check.
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