Microsoft will end support for Skype version 7 in November

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We’re continuing to work on your most requested features. Recently we launched call recording and have started to roll out the ability to search within a conversation. You’ll soon be able to add phone numbers to existing contacts, have more control over your availability status, and more. As we continue to focus on and improve Skype version 8, support for Skype versions 7, and below will end on November 1, 2018 on desktop devices and November 15, 2018 on mobile and tablet devices. Although you may be able to use older versions for a little while, we encourage you to update today to avoid any interruption.

Source: Upgrade to the latest version of Skype | Skype Blogs

See also: Microsoft shares more info on the update to Skype version 8 - Windows 10 Forums