Hello,
Yes you will have to make a new child theme for the pro version, even though all your customizing options will be safe, some of the changes like function overriding, style changes will not show any effect the pro version of the theme if done on the free version of the child theme.
You can try and replicate the child theme and change the template name to education hub pro and see what changes on your child theme effect the pro version and what does not have any effect on it.
Hope you understand.
Best regards.