First of all, you need to open this link:
https://app.funeasylearn.com/redeem
Follow these instructions to redeem your code for a subscription for 1 language course here:
https://youtu.be/OwKvVpoCPvU
Or follow these instructions if you need to redeem your code for a subscription to all the 34 language courses:
https://youtu.be/JK-54ls-9Xs
Note: You need to sign in to the app with the same account with which you have made the purchase.