UNAUTHORIZED LNDG; LNDG WITHOUT CLRNC.

Narrative

I WAS VECTORED TO A VISUAL APCH RWY 12L AT STL. CONDITIONS WERE VMC AND ALTHOUGH DAWN WAS JUST STARTING IT WAS STILL DARK ENOUGH THAT I WAS PICKING OUT THE RWY FROM THE 2 PARALLEL LINES ON THE APCH LIGHTING SYSTEMS. THE APCH AND TOUCHDOWN WERE NORMAL BUT WHEN ROLLING OUT I NOTICED THAT TWR HADN'T SAID ANYTHING ABOUT SWITCHING TO GND OR WHICH TAXIWAY TO TURNOFF AT. I ASKED THE FO TO INQUIRE ABOUT IT. AT THIS POINT APCH CTL SAID WE SHOULD CONTACT TWR FOR THE INFO WE BOTH LOOKED AT EACH OTHER AN ASKED OURSELVES 'DID WE EVER GET CLRNC TO LAND?' HE THOUGHT WE DID BUT WASN'T SURE. I JUST WASN'T SURE. TWR DIDN'T GIVE ANY INDICATION THAT ANYTHING WAS WRONG AND NATURALLY I DIDN'T WANT TO PRESS THE ISSUE. IN THIS JOB FLYING AT NIGHT INTO A LOT OF ARPTS WHERE APCH CTL; TWR AND GND CTL IS ALL THE SAME PERSON; THEREFORE IT DIDN'T SEND OFF ANY ALARMS WHEN WE WEREN'T TURNED OVER TO TWR ON APCH AS IT SHOULD HAVE. I STILL DON'T KNOW IF APCH CLRED US TO LAND OR NOT ITS EMBARRASSING ENOUGH TO SCREW UP AND EVEN MORE IF YOU CAN'T REMEMBER IF YOU HAVE OR NOT I REALIZE NOW THAT I'M GOING TO HAVE TO KEY MYSELF TO ASK APCH CTLS IN THE FUTURE IF THEY WANT ME TO SWITCH TO TWR FREQ WHEN THEY CLR ME FOR THE APCH. I USED TO THINK ABOUT THIS AT THE OM BUT IN THIS CASE THE TURN TO FINAL WAS INSIDE THE OM.