Paid Windows 10 App Plex Cannot be Activated



I purchased the Plex app from the Windows App Store on 1-9-2014.

When I log in my tablet(Atom), the Win10 Plex UAP app doesn't recognize that I am the owner of this app under Setting, Account. However it is recognized fine with my laptop (i7). Both are under same Microsoft Account.

Any reason?

Thank you.