Great app, but the ad-free version doesnt work

This is a great application, offering a very pleasant way to learn. It is particularly useful for learning a language like Hindi, which uses a different script. I did pay for the ad-free version, but unfortunately that didnt do anything at all, I still see the ads (not that annoying though) in between activities.

Dst307 about 6000 Words - Learn Hindi Language for Free, v2.6