Sound Recorder for computers

My Granddaughters like to sing into a computer microphone.
At first I tried using windows recorder but that would not due as the time is short on that.
I found an open source program.
Open source means free to use.
Audacity® is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows

It will let you record for a very long time.
If you are really into it I recommend a usb microphone.