[lights0123]

That was 8 years ago. Mountain Lion came out before even Windows 8, where even Microsoft was charging for upgrades too before releasing the final version (major version, not build version) of Windows.

[fastball]

Doesn't MSFT still charge for every OS update?

[fomine3]

Windows 10 is the last Windows for client in current plan. MS continuously upgrades features on Win10 instead.