The middle digit of the last 3 numbers represents when within the month you must renew. Para sa 6, the deadline was between the 8th and 14th of August. So pwede ka na hulihin pag di ka pa nakakarehistro.
I think you have to register your ride coz your middle digit 6 means you have to register it during the 2nd week of August, but you are still registered till Aug. 31, 2009. Hope this clears your concern.