He 'registered as' a Republican. = He 'is registered' (to vote) 'as' a Republican.
The students 'registered for' classes. [=the students enrolled in classes]
The team finally 'registered' a victory after losing three games in a row.
(..) Like you missed me. This is my girl, Natalie. Oh, the heartbreaker from the carshop. The doctor? - Actually, she's... - I'm a registered nurse. Nurse? Right, sorry. You were supposed to be here two hours ago, man. And that's our irresistibly charming, Eric. (..)2013 Evil Dead