I need to re-download Microsoft 365 for mac which I can use until 12/2021

Log into your Microsoft account and download it.

https://account.microsoft.com/account?lang=en-us

angelafrompowell wrote:

I need to re-download Microsoft 365 for mac which I can use until 12/2021

I purchased it on Dec 6th.

To activate a Microsoft Office 365 subscription you simply enter the email address you used when you extended the subscription with Microsoft.