Your Gravy+ membership is managed by the app store subscription tools through Apple and Google.
Option 1 - from the Gravy app
Tap the Gravy+ member button on the More menu (4 dots on the bottom right of the navigation bar)
Scroll down to the "Your plan" section
Tap the purple button to manage your membership
This should open your phone's subscription settings
Option 2 - from the App Store app
Open to App Store or Google Play app
Tap the "Profile" icon
Go to your Subscriptions
Tap Gravy from the list of subscriptions
Follow the prompts to change your plan or cancel the subscription
If you have any issues, please reach out to support@gravy.co and we'll be happy to assist 😎