From the 1st of March, people will no longer be able to log in using :
Version 7.16 (and older builds) of Skype for Windows
Version 7.18 (and older) of Skype for Mac
Its a relatively painless update but if you don’t update you wont be able to continue using the service until you do.
Microsoft say :
“Because we want to provide our users with the best possible Skype experience, necessary changes must be made along the way. So, beginning March 1, users running older versions of Skype for Windows desktop (7.16 and below) or Skype for Mac (7.0 to 7.18) will no longer be able to sign in.”
You can get the latest update HERE.