Multisite Licence

Hi,

For the site I will create I will use multisite but did not decide if it should be subdomains or subdirectories. However, it will be the same site but I will use the menu items as divisions. The other sites will be like subdomains but not a different site for the third person or customer. The main site will have just one page navigation and the other ones will be like branches.

Should I buy the theme for every one of the subdomains or not? What do you think?

Best Regards