Your BIOS may contain something called SLIC (software licensing description table), updating your BIOS may have reseted that and you lost the Licensing store.
I recommend you re-create it manually, to do that you must:
Make sure you are logged in as Administrator.
Click the Start button and type "cmd.exe" in the search field and open it.
Type(fallowing the order of the numbers):
1) net stop sppsvc
2) cd %windir%\ServiceProfiles\NetworkService\AppData\Roaming\Microsoft\SoftwareProtectionPlatform
3) rename tokens.dat tokens.bar
4) cd %windir%\system32
5) net start sppsvc
Now you should see Windows Activation dialog appear. Proceed by typing your Windows product key.