If your membership is paid through Google Play, you will need to turn off your auto-renewal through Google Play directly. Here's how:

1. On your Android phone or tablet, open the Google Play Store .
2. At the top right, tap the profile icon.
3. Tap Payments & subscriptions  Subscriptions.
4. Select JibJab. 
5. Tap Cancel subscription.
6. Follow the instructions.

You can also view these instructions on Google's Help site: https://support.google.com/googleplay/answer/7018481

If your membership is not paid through Google Play, please check out these articles: 

Cancel Subscription via Apple

Cancel Subscription via JibJab