As predicted MS have cancelled this https://www.ozbargain.com.au/node/322749
"Dear valued customer,
Thank you for redeeming your 3-month trial subscription to Microsoft Groove Music. We’re reaching out to you to let you know that we experienced an issue with your redemption code which extended the 3-month trial. We will be adjusting the access to the 3-months as awarded by the pass which will be reflected in your account."
How annoying.. I was all set until late 2019!
Just got the email too! Was in the middle of posting to this forum and it detected a duplicate haha oh well deleting the app now