If you find yourself needing to break out license usage statistics often, you might find it helpful to check out the License Usage app, which includes queries for license usage by index/sourcetype/etc.
But in particular, this question had a good answer that breaks out license usage by indexname and sourcetype:
index=_internal sourcetype=splunkd source=*license_usage.log type=Usage idx=YourIndexHere | stats sum(b) as usage by idx st | eval usage_MB=round(usage/1024/1024,3) | rename idx and index st as sourcetype
index=_internal source="*/license_usage.log" component=LicenseUsage idx=<your index> | timechart sum(b) AS b BY st
In the license usage events
idx is the index and
st is the sourcetype that the licensing metrics are detailing.
Start here -
index=_internal source=*license_usage.log* Usage | eval s=coalesce(s,"unknown"), eval st=coalesce(st,"unknown") | stats sum(b) as bytes by idx s st