when did the last lab test of patient 64185 in 07/this year happen?
select labevents.charttime from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 64185 ) and datetime(labevents.charttime,'start of year') = datetime(current_time,'start of year','-0 year') and strftime('%m',labevents.charttime) = '07' order by labevents.charttime desc limit 1