Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Greetings!
This is Tin, I'll do my best to help. When you purchase MS Office 365 subscriptions from MS Store, usually it doesn't include Product key anymore, it will automatically associated with your MS Account.
If you have a Product key, you may try to redeem it from https://office.com/setup
You can also check your purchase from this link https://account.microsoft.com/billing/orders
To check your subscription to make sure that it's already active, you may check it from https://account.microsoft.com/services.
In case you really can't find your subscription on your account. It would be best to reach the MS Accounts & Billing Support:
Kindly open this link: https://support.microsoft.com/contactus/
Ensure that your MS Account has been signed in
Type "Chat with an agent" and hit Enter.
Please click the "Contact support"
Please select the "Products and services"
Please follow the prompts to connect with a live agent.
You may also choose the "Call me back" option if you prefer to receive a call.
Once you're connected to the Live Agent, please let them know about your issue so they could check your account and address your concern.
Thank you,
Christine L