(I assume you are referring to the ingest based license model here)
If you are in a Splunk managed Splunk Cloud environment, you can take a look at the Volume License dashboard that is part of the Cloud Monitoring Console. On that dashboard, the _telemetry index is used. That index typically has a retention period of 720 days, so you should be able to go back past 2 months.
Here is the query used on that page:
(host=*.*splunk*.* NOT host=sh*.*splunk*.* index=_telemetry source=*license_usage_summary.log* type="RolloverSummary")
| bin _time span=1d
| stats latest(b) AS b by slave, pool, _time
| timechart span=1d sum(b) AS "volume" fixedrange=true
| eval GB=round((((volume / 1024) / 1024) / 1024),3), Volume=GB
| fields - GB, volume
... View more