The following Splunk Search will show license usage over the past 30 days:

index=_internal source=*license_usage.log type="RolloverSummary" earliest=-30d@d   | eval _time=_time - 43200 | bin _time span=1d | stats latest(b) AS b by slave, pool, _time | timechart span=1d sum(b) AS "volume" fixedrange=false | join type=outer _time  | fields - _timediff  | foreach * [eval <<FIELD>>=round('<<FIELD>>'/1024/1024/1024, 3)]