Hello LynneE1,
Welcome to Microsoft Community.
I am a Microsoft 365 user just like you, I hope you are doing well?
Do you want to redeem a product key or you wish to transfer Microsoft 365 subscription to another account?
If you he Microsoft 365 product key, you need to redeem the product key to your Microsoft account in order to install and activate Office on your PC.
To redeem the Office 365 product key:
Step 1: Go to www.office.com/setup or Microsoft365.com/setup.
Step 2: Sign in with your Microsoft account, or create one if you don't he one.
Step 3: Enter your product key, without hyphens, if prompted.
Step 4: Follow the prompts to finish the redemption process.
Once you he redeemed the product key to your Microsoft account, you can then install Office 365 by signing in https://office.com/myaccount on the PC .
You will find Office 365, click install. Once you he successfully completed installation, you need to sign in your Microsoft account in any Office app to activate Office.
Find guidance to install Office: https://support.microsoft.com/office/4414eaaf-0478-48be-9c42-23adc4716658
Source: https://support.microsoft.com/office/0a82e5ae-739e-4b92-a6f4-2ec780c185db
Whatever your reason, you can manually transfer Microsoft 365 Family or Personal subscription from one Microsoft account to another.
The specific actions to do this transfer manually will depend on your situation, but it will involve purchasing a new Microsoft 365 subscription and then cancelling your existing one.
Source: https://support.microsoft.com/office/9ea55e89-ffcb-4da3-9c73-7051d75a7221
Did you mean you want to share your Microsoft 365 subscription with another account?
With Microsoft 365 Family subscription, you can share your subscription benefits with up to five other people. You do this by sending each person an invitation or by adding them to your Microsoft family. After each person accepts the invitation, they can sign in (using their own Microsoft account) to www.office.com to install Office on their devices and access their own 1 TB of OneDrive storage.
How to invite someone to share your Microsoft 365 Family subscription benefit:
Sign in to your Microsoft account, Sharing page using link below. Be sure to use the same Microsoft account that you used to set up your Microsoft 365 Family subscription.https://account.microsoft.com/services/office/sharing
Select the Start sharing button. On the Share your subscription pop up, choose one:Invite via email
Enter their email and select Invite.
The email you use to invite them should also be the email they use for their shared Microsoft 365 subscription.
Invite via link
Select the Copy button to send the link via email, text, or other message to the person you want to share with.
When they click the link and sign in with their Microsoft account, they'll be added to your subscription. If you want to share with more than one person, create a separate link for each person.
If you chose to invite via email in step 3, select Invite if you want to add this person to your Microsoft family. You can always add them later too. After they accept your invitation, they can sign in (using their own Microsoft accounts) to www.office.com to install Office on their devices and access their own 1 TB of OneDrive storage.Source: https://support.microsoft.com/office/b389b9ce-3ae3-4a82-9017-39d79972fcba
Please let me know if you need more assistance.
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Warm Regards