Hi ,
If you don't have an active subscription and tried to redeem it and it didn't work, contact Microsoft support. Also, contact the store(G2A) where you purchased the code and let them know it's not working, just in case.
The best way to contact Microsoft is through the Home chat. Access the link below and type "Account." Below, there will be a Contact Support option.
Enter your details to open the chat, and a Microsoft agent will come to assist you.
https://support.microsoft.com/home/contact
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Thanks