You can redeem the discount code for mediteo premium by first finding the corresponding notification under More → My news.

For iOS:

A discount code will be copied automatically and you will be redirected to the subscription page. There, you can paste the discount code when purchasing mediteo premium and receive the corresponding price reduction.

For Android:

You will be redirected automatically to the subscription page. There, you can buy mediteo premium with the price reduction from the offer.