Hello @dddd
Thanks for reaching out to us, I am sorry, currently we are not supporting migration models between different subscriptions.
But if you are thinking about upgrading your free subscription to paid subsciption, you don't need to migrate all your resource. You can easily upgrade your current free subsciption to paid subscription in Azure Portal as below screenshot. I am sorry for the product limitation.
Please let me know if you have any other questions and hope above helps.
Regards,
Yutong
-Please kindly accept the answer if you feel helpful to help the community, thanks a lot.