I would like that the usage of enterprise edition is referring to the actually database storage or the summation of all input data before processing ?

Data usage calculation of enterprise edition

macko003 November 19, 2018, 9:22am 2

As far as I know it use the System/overview Outgoing traffic data.
https://community.graylog.org/t/graylog-system-overview/5177

Topic		Replies	Views
Graylog License Graylog Central (peer support)	4	1028	June 13, 2018
Graylog Enterprise Under 5GB/day Support Graylog Central (peer support)	3	600	April 11, 2019
Graylog Outgoing traffic Graylog Central (peer support)	3	3658	November 14, 2018
GB/day usage volume Graylog Central (peer support)	2	285	August 12, 2021
Graylog System OverView Graylog Central (peer support)	3	1404	May 22, 2018