So you could use Decision Warehouse that is part of the execution server to trace each execution. This can include which rules have been fired during the execution, but depends on what filters you apply.
Here is the documentation on DW and how to set it up: http://pic.dhe.ibm.com/infocenter/dmanager/v8r5/topic/com.ibm.wodm.dserver.rules.res.managing/topics/con_res_dw_overview.html