Outlook.com Premium is subscription based (USA only) $19.95/yr now, will be $39.95/yr (eventually). Ad free version - maybe this is a glimpse into what is to come from Microsoft. Free vs Premium. https://betanews.com/2017/02/14/microsoft-outlook-com-premium/
That Outlook.com Premium email address? Gone, unless you get an Office 365 subscription February 3, 2020 https://betanews.com/2020/02/03/outlook-com-premium-email-address-gone/