Every time a released change set is applied on a system an entry is recorded in the apply history for the change set on the system in question. To get a complete history of when a change set was applied, a user would look at the history across the systems in the landscape.
In the example used previously where the "Release 0618" change set is transported from development to testing to production: When the change set is transported and applied on the testing system, an entry is created on the testing system in the apply history for the "Release 0618" change set. When the change set is transported and applied on the production system, an entry is created on the production system in the apply history for the "Release 0618" change set.
The apply history details include the user who applied the change set and the date and time with the change set was applied.