Make sure you don’t have an active restriction on buying in-app purchase products.
You can find out more information regarding in-app purchases here:
iOS: https://support.apple.com/en-gb/HT204396
Android: https://support.google.com/googleplay/answer/1050566?hl=en
Alternatively you can purchase a subscription online here:
https://payment.languagedrops.com/purchase
Language learners from Russia: Unfortunately, there is no way for us to bypass any sanctions or payment restrictions on Russia at this time. You can currently only purchase Drops in the app stores, or online here:
https://app.languagedrops.com/#/purchase/
Language learners from China and Iran: We are hard at work improving the app and adding more payment options, so please stay tuned!