Hello
I want my refund for my lifetime license, I realized that I can’t learn much with this app and I don’t use this app this. So please refund me as soon as possible. Thank you
Hello Vivian,
You should follow these instructions
How do I cancel my subscription?
To cancel the automatic renewal for your Memrise subscription, you can log in on a computer, click on your Profile icon in the top right corner, then select 
Settings > 
Account .
Please note : if you subscribed via Apple App Store (iOS) , you will have to follow these instructions instead.
Cancelling your membership will automatically cancel your subscription’s auto-renewal. The paid features will remain active until the end of your current subscription period.
Another option is to follow this link and click the contact us button (red) and give them the details they need but be warned it takes a good while for them to deal with it but be patient they will sort it for you.
Help page 
https://memrise.helpshift.com
I hope this answers your question adequately, they move slowly due to the volume of messages on here.
Roy.