All template inside the plugin can be customized and modified in a theme (or Child Theme). WooCommerce License Keys will give priority to any copy, of a template, found inside the activated theme.
Any WooCommerce custom template (including this plugin templates) should be located at:
[theme]/woocommerce
Regular plugin templates
The templates in the regular version of the plugin (found at WordPress.org) are located at:
woo-license-keys/templates
Extended plugin templates
The templates in the extended (premium) plugin are located at:
woocommerce-license-keys-extended/templates
Example
For example, to customize the template used to display a customer license key code in WooCommerce’s “My Account” page, the following template should be copy from:
woo-license-keys/templates/myaccount/view-license-key.php
Into:
[theme]/woocommerce/myaccount/view-license-key.php