Hi @강현진 ,
I suggest you check the status of your account in Office 365 portal:
- Go to portal.office.com
- Click on My Account
- Look at the Subscriptions panel
- Check for Office 365
If you see it, you have the correct license and that’s not the problem. If you don’t see it, check that you are signed into the correct account. And check if the devices are limited, you can disable the device which is not used.
Try this method and let me know if you need more help, I'm glad to help you.
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.