Hello,

If you rearrange your current site as a multisite https://wordpress.org/support/article/create-a-network/ one license would be enough.

If you create a site of different domains you will require a license for each domain.

WPML is a time-consuming plugin, however, it is one of the best, take one more try and contact their support sot that would help. If you have questions for translating the header and footer let us know we shall help.

Best Regards