Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi SuzF,
Thank you for your message in this forum.
According to your description, it seems that you have subscribed Office 365 and you want to know if you need to purchase additional virus protection software.
Generally, if you purchase Office 365 subscription from Microsoft Official channel, you don’t need to purchase additional virus protection software, you can only pay for Office products. And you can use Office products normally without additional virus protection in your computer.
And if you are using Windows 10, Windows 10 delivers comprehensive, built-in and ongoing security protections you can trust – including Windows Defender Antivirus, firewall, and more. By staying up to date, you’re assured of the latest features and protection – at no extra cost to you. For more details, you can refer this article: The most secure Windows ever - and built to stay that way
Best Regards,
Sukie