Because it is a legacy product, you cannot buy it through standard retail channels. Instead, access is managed through specialized professional subscriptions:
When it first arrived in October 2013, it was a major shift for Microsoft, moving the IDE toward the "Cloud OS" vision. buy visual studio 2013
Description of Visual Studio 2013 Update 4 - Microsoft Support Because it is a legacy product, you cannot
This is the primary legitimate way to get older versions. If you have an active Visual Studio Subscription , you can log in to the subscriber portal to download the ISO and product keys for legacy editions like 2013. Because it is a legacy product