Since the release of windows 8 there was change in features between prof and other editions.
The details are explained here
Windows 8 Enterprise | Enterprise Software | Enterprise Edition
As you may have noticed bitlocker is no longer limited to enterprise os, you now have this feature on windows 8 professional as well.
So, let’s activate it.
Open your apps and look for bitlocker.
Start the encryption wizard
Turn on bitlocker
You now have a new option of saving the recovery key to the ms account. I choose save to file because my logon user is not an admin.
I choose the option of only encrypting used space.
Run the bitlocker check and the tablet will be rebooted.
You can continue working while encryption is in progress.