PLT OF A SMA SEL FAILED TO CLOSE IFR FLT PLAN AFTER LNDG AT AN UNCTLED ARPT AT NIGHT.

Narrative

I FAILED TO CLOSE MY IFR FLT PLAN AFTER LNDG AT ORLANDO EXECUTIVE ARPT. ON THE ILS APCH INTO ORL; CTLRS TOLD ME I COULD CLOSE MY FLT PLAN AFTER LNDG. THE RWY WAS PARTIALLY OBSCURED; AND A TSTM WAS IN PROGRESS N OF THE FIELD. ALTHOUGH I DID HAVE THE RWY LIGHTING SYS AND RWY END IN VIEW; I FELT IT WAS PRUDENT TO CANCEL AFTER LNDG DUE TO THE RWY OBSCURATION. ON LNDG; I COMMENCED TO CALL APCH ON THE FREQ GIVEN. I MADE MANY ATTEMPTS TO MAKE CONTACT WHILE TAXIING TO THE TERMINAL AREA; BUT RECEIVED NO RESPONSE. ARPT FACILITIES WERE CLOSED. MY PAX AND I HAD PRERESERVED A RENTAL CAR; AND ON ARRIVING AT THE FBO AREA; A REPRESENTATIVE WAITED FOR US WITH THE CAR. IN THE PROCESS OF ACQUIRING THE VEHICLE AND OFF-LOADING THE ACFT; I COMPLETELY FORGOT TO CALL AND CANCEL THE FLT PLAN. ON ARR AT OUR HOTEL; I REALIZED WHAT HAD HAPPENED. I PHONED FLT SVC TO ADVISE THEM OF OUR ARR AND CLOSE THE FLT PLAN. PREPARING TO DEPART SUNDAY MORNING; WE WERE ADVISED BY FBO PERSONNEL TO CALL APCH CTL. WE WERE INFORMED BY CTL THEY HAD HELD SEVERAL ACFT FROM OPS WHILE THEY SEARCHED THE FIELD FOR OUR ACFT; AND THAT OPERATORS OF THE EFFECTED ACFT WANTED MY NAME AND ADDRESS. I SUPPLIED THE INFO REQUESTED AND WE DEPARTED FOR HOME. THE BOTTOM LINE WAS; I FORGOT TO SATISFY THE REGULATORY RESPONSIBILITY TO CLOSE THE FLT PLAN; CAUSING DELAYS AND DIFFICULTIES FOR CTLRS; OTHER OPERATORS; AND POLICE AGENCIES SEARCHING FOR US. CONTRIBUTING FACTORS: WE WERE TIRED. WE HAD BEEN TOO LONG IN THE COCKPIT; FLYING SINGLE ENG FROM MINNEAPOLIS TO ORLANDO ON THE SAME DAY; IN 3 LEGS; 11 HRS FLT TIME. THE LAST 2 LEGS WERE IFR; THE LAST LEG NECESSITATING NAVIGATING AROUND ACTIVE TSTMS.