How to record sound 24/7

I want to record sound from a particular microphone on a Windows 7 for an extended period of time.
The computer is on 24/7. How can I achieve this?

Background
My neighbor is causing problems saying that I'm making noise even when I am not home. I thought of the idea of recording sound levels in my flat for factual evidence in-case this ever turns sour.

_{Short answer}
Create a scheduled task and use ffmpeg together with a batch file to record your microphone.

_{Long answer}

1. Download ffmpeg-XXXX-win32-static.7z for Windows and extract it with 7-zip or Winrar

2. Copy Bin\ffmpeg.exe to a folder of your choice (You can delete the other files & folders)

3. Create a new text file and paste the following code.
   Save the file as record.cmd in the same folder as your ffmpeg.exe

   @echo off
   mkdir "My records"
   set outputpath=My records\record_%date:~-2,2%%date:~-7,2%%date:~-10,2%_%time:~-11,2%%time:~-8,2%.mp3
   ffmpeg -f dshow -i audio="My microphone" -y -t 01:00:00 "%outputpath%"
   

4. Replace My microphone with your own microphone name.
   To get the name, open a CMD Window and head over to your ffmpeg.exe.
   This command lists all available devices: ffmpeg -list_devices true -f dshow -i dummy

5. Create as scheduled task (Win+R » Taskschd.msc) and point it to your record.bat.
   Let it run each full hour so ffmpeg can split your audio in 1-hour files.

The result after some hours

Additional help

• All used commands are explained at the ffmpeg documentation
• It is possible to execute the whole process in a hidden window or in the background
• It is also possible to start and stop the task per shortcut
• Change the record time ("01:00:00") or output path ("My records\record") to your needs