When you purchased the Premium, you should have immediately setup your account to sync then.
One of the accounts has to be empty and not have "entries" in it in order for it to initially sync.
So with that said, I think probably the easiest thing at this point for you to do is make a new profile on your PC Premium Version that is empty and has NO entries in it yet.
Then set that profile/account up to sync with your online account.
It should work exactly how you want it to after that