From March 1, people will no longer be able to log in to version 7.16 of Skype for Windows desktop and older versions, and version 7.18 of Skype for Mac.
According to a report in Venture Beat, both the versions came out in December 2015.
"If you're one of those users, all you'll need to do is download the new update," the Skype team said in a blog post on Friday.
To improve Skype, Microsoft has rolled out various changes like migrating the app to its Azure public cloud infrastructure, and adding chatbots.
"We've poured our energy and passion into creating something truly special, and this is just the beginning," Skype added.