Users on one account.

Yes, but it depends on which Microsoft 365 plan is on the account.

• Microsoft 365 Family can be shared by the subscription holder with up to five other people.
• Only the subscription account holder can share the subscription.
• If the invited person is already part of another shared subscription, they cannot be shared again.
• If Share subscription does not appear on the Subscriptions page, the account likely does not have Microsoft 365 Family.

For this situation, check these items:

1. Sign in to Services & subscriptions and confirm which subscription is active on the account.
2. If it is Microsoft 365 Family, verify that the subscription was actually shared and that shares are still available.
3. Make sure the wife accepted the sharing invitation and joined the Microsoft family group. The subscription dashboard updates only after Join now is selected and the family group is joined.
4. If the wife is seeing an expiration notice, that often means the Office apps are signed in with a different Microsoft account, or a separate subscription is still attached to that account.
5. If the subscription was recently renewed and Office still shows expired, close all Office apps and open them again. Signing in again with the Microsoft account associated with the subscription may be required.

Also note:

• A Microsoft account can have only one Microsoft 365 Family subscription associated with it.
• Redeeming multiple Microsoft 365 subscriptions on the same account extends the subscription time up to 5 years; it does not increase the number of people who can use it.
• If support is needed for more than 6 people, Microsoft recommends a business subscription or volume licensing.

References:

• Get help with product key errors on Office.com/setup
• Troubleshoot sharing a Microsoft 365 subscription
• Problems renewing a Microsoft 365 subscription
• About accounts in Office