How to find the most pga consumer sql statement?

[PAVB]

I wanted to check if Oracle keep pga consuming statistics per session?

Yes... at least as long as the session is in the system - check v$sesstat

Feel free to customize query below to show the data you are looking for as well as the particular session/s you are interested in. Found this query some time ago, find it usefull.

set pages 500 lines 100 trims on
clear col
col name     format a30 
col username format a40
break on username nodup skip 1

select   vses.username||':'||vsst.sid||','||vses.serial# username, 
         vstt.name, 
         max(vsst.value) value 
from     v$sesstat  vsst, 
         v$statname vstt, 
         v$session  vses
where    vstt.statistic# = vsst.statistic# 
     and vsst.sid = vses.sid 
     and vstt.name in ('session pga memory','session pga memory max','session uga memory',
                       'session uga memory max','session cursor cache count',
                       'session cursor cache hits','session stored procedure space',
                       'opened cursors current','opened cursors cumulative') 
     and vses.username is not null
group by vses.username, vsst.sid, vses.serial#, vstt.name 
order by vses.username, vsst.sid, vses.serial#, vstt.name
;