Usando o novo Outlook no Windows para gerenciar e-mails pessoais, calendário e contatos
Hello,
Technically, your subscriptions and Windows licenses are tied to the Microsoft account entity itself, not the specific email name. Since aliases are just different doorways into the same account, you should retain your Office 365 subscription and Windows activation after making the new alias the primary one.
Be extremely careful about deleting the old email address. If that old address is a Microsoft domain (like Hotmail, Live, MSN, or Outlook), removing it is immediate and permanent. You will never be able to get it back, and you will stop receiving any emails sent to that old address.
Unless you have a specific reason to delete it, the best practice is to simply leave it there as a secondary alias so you don't miss any old mail or lose access to other services where you might have used that email to register.