Microsoft no longer sells Windows Vista Home Premium directly, as retail distribution ended in October 2010 and OEM supply ceased in October 2011. Official extended support for the operating system also concluded on April 11, 2017.
You can find new and pre-owned physical copies of Windows Vista Home Premium through various online retailers: Windows Vista - Microsoft Lifecycle buy windows vista home premium
Since there are no legal or official digital ISO downloads currently available from Microsoft, you must purchase physical media from third-party marketplaces to obtain a valid license. Microsoft no longer sells Windows Vista Home Premium