Yes. The WP 2FA licensing is based on the number of users and not on the number of websites. Therefore if you have a 100-user license, you can use it on as many websites as you want as long as the number of users who are using 2FA does not exceed 100. For example, if you have a 100-user license and you have five websites with 20 users on each who are using 2FA, you can use the same license key on all the websites.