Duolingo for Business provides employers the opportunity to purchase bulk subscriptions to Duolingo Plus at a discounted price to distribute to their employees. Employers may purchase between 10 and 1000 subscriptions (if you require more than 1000 subscriptions, please fill out this form). All subscription codes are redeemable for 1 year of Duolingo Plus. These subscriptions do not renew automatically.
More information and FAQs can be found here.