The Record Instant Macro command in the Macros menu records a macro just like Macros|Record Macro does. The only difference is that EditPad Pro doesn't ask you for a name and keyboard shortcut for the macro. The only way to play back the instant macro is with Macros|Play Instant Macro.
Only one instant macro is preserved at a time. Recording a new instant macro deletes the previous instant macro without warning.
Use instant macros when you want to quickly record and play back a group of keystrokes a few times.