Hi,
You can try this: first, repair Office completely by opening Control Panel > Programs > Microsoft 365 > Change > Online Repair (not Quick Repair), then restart your device and open PowerPoint or Word again. Second, make sure your Windows and Office are both fully updated, go to Settings > Windows Update and File > Account > Update Options in any Office app. Third, if the issue persists, try signing out of your Microsoft account in all Office apps, then sign back in to refresh your license and sync settings.
Can I ask, are you using an Office 365 subscription or a standalone version (like Office 2019)? Also, do you notice this message appearing on all your Office apps or just one (like PowerPoint only)?
Kind regards,