These details might be in-memory (internal) (might be in IS core audit), to get these details via service use “wm.server.query:getServiceStats”
To make this service viewable in Designer add the below IS extended setting and refersh the Designer console.
watt.server.ns.hideWmRoot=false
Also, there are other tools/utilities available like WmRichStatistics and few others (do not remember the names now) but you can find them on this forum.
this data is only stored in memory.
If you have doubts regarding the correctness of the cached data you should set the cache expiration to a shorter period so that the data will be updated more frequently.
Service Usage data should either be stored in ISCoreAudit database or in a log file.
Only the cached data is stored in memory and will be removed after cache expiration has elapsed.
15 minutes cache expiration sounds reasonable.
Additionally to the cache expiration the cache will be cleared and reinitialised during IntegrationServer startup as the cached data (input/output) is stored in the JVM Heap memory.