Can I pass onwership of this template to a client?
Is it possible to give the ownership of a template to another themeforest user?
Yes, sure. You can pass the license ownership to your client. You can basically send the license file downloaded from Themeforest Downloaded page.
Thanks for the answer Sean,
You mean the license is in the file I downloaded when I bought the theme?
Then, the client how can receive the updates? should she upload the license to her account?
Uploading licenses to client's account is not possible with Themeforest.
To get the updates the client needs to access the Themeforest account that was used to purchase the license. Also, you can assist to create a Themeforest account for your client and purchase the license.