You can bring up the histary dialog with the keyboard (Alt+Up arrow) or with the main menu in "Search" then "History".
This dialog box displays the history of all functions you have visited during the current session. A function is added to the history display after the cursor stays within it for more than a fixed number of seconds, in this case 8 seconds. You can change this value in the configuration options at the lower right.
You can change here too the maximum number of functions the system will remember, in this case we have 15. If you set this number to zero you disable this feature.