Purchased 365 on wrong microsoft account, help!

The Microsoft 365 subscription cannot be moved from one Microsoft account to another, and Microsoft does not support merging or reassigning accounts or Outlook.com addresses between accounts.

Key points based on the scenario:

1. The subscription is tied to the Microsoft account used at purchase
   • The Office/Microsoft 365 subscription is permanently associated with the Microsoft account that was signed in at the time of purchase (in this case, the @yahoo.co.uk account).
   • It cannot be transferred to the @upleadonmortgages.co.uk account or merged between the two accounts.
2. Why adding the work email as an alias fails
   • The error message about the email belonging to an organization is expected behavior: organizations can restrict using their domain addresses as aliases on personal Microsoft accounts.
   • When an address is recognized as a work or school account (Microsoft 365 or Azure AD), it generally cannot be added as a personal alias on another Microsoft account.
3. What can be done now
   • Continue to use the subscription under the @yahoo.co.uk Microsoft account (the one that owns the license) and sign into Office apps with that account.
   • Use the @upleadonmortgages.co.uk address only as the email account in Outlook (added as a mailbox), not as the Microsoft account that owns the subscription.
   • If the @upleadonmortgages.co.uk address is part of an organization’s Microsoft 365 tenant, the organization’s admin can assign a separate Microsoft 365 license to that account if needed; it will still be a different subscription from the one on the @yahoo.co.uk account.
4. Why the desired move is not possible
   • Existing Outlook.com or Microsoft email addresses are already their own Microsoft accounts and cannot be moved or merged into another Microsoft account.
   • Microsoft does not allow account merging or recycling of Outlook.com aliases, so an address cannot be “taken” from one account and attached to another.

For any billing or subscription-change options (such as cancellation and repurchase under the correct account), direct contact with Microsoft Billing Support is required, as self-service tools cannot reassign the subscription between accounts.

References:

• How to add an email address or phone number to your Microsoft account
• "Something went wrong" with error ADDriverStoreAccessNonLocalException
• Add another alias to your account and make it the primary alias
• How to add an existing outlook.com account to my existing microsoft account? - Microsoft Q&A
• Add email addresses
• Add an email account to Outlook for Windows