Error code: 0xC004C003 win8 to win8.1

Goody day, need help how to fix Error code: 0xC004C003. i update my win8 pro w/ MC (OEM key) to win8.1 Pro w/ MC through windows store. now i got that error and the watermark. well i thought when i update my OS, i still got the OEM key from my past OS. and yeah. im wrong.. any help how to fixed the water mark and bring back my oem key? any other positive way or suggestion for it before i used activator. Thanks