MP3 Skype recorder v. 4.43 (download) works with the following Skype versions:
- Skype app is a version for Windows 10 only. Tested with Skype version v.12.1815.2100.0
- Skype for desktop. MP3 Skype recorder tested with latest version 8.25.0.5
- Skype for business
- Skype classic is now obsolete version. It is still supported with recorder. Unfortunately  download is now removed from Skype.com. This version had Skype API. Skype is moving its network infrastructure from p2p to the cloud and Skype classic will stop working. More information on these changes can be found on Skype webpage https://support.skype.com/en/faq/FA12381/what-does-it-mean-that-skype-is-moving-from-peer-to-peer-to-the-cloud

! Please note. You might need to restart MP3 Skype recorder if you just moved from Skype classic to Skype for desktop or Skype app.