Twitch Prime Subscription Reminder v1.0.6resigned1
This is an alternative to the "Prime Subscription and Loot Reminder Extension" inside twitch.tv that you can enable for your favorite streamer.
It will switch the purple "Subscribe" button to a bright orange when your free subscription with Amazon Prime is ready to be used.
The Google Chrome extension is available at https://chrome.google.com/webstore/detail/lkojkjhbgnhoepnajfllnjffcheahpco