when did the last lab test of patient 20165 until 09/2100 happen?
select labevents.charttime from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 20165 ) and strftime('%y-%m',labevents.charttime) <= '2100-09' order by labevents.charttime desc limit 1