Changing your subscription from annual to monthly will take effect at your next renewal date. For example, if you want to change from monthly to yearly and your current monthly subscription renews on the 5th of next month, your change to annual will take place on the 5th, and that is when you will be billed for the yearly amount.
Follow the instructions below, depending on how you initially subscribed to your account:
Google Play
From the Strava app on Android:
Go to the You tab and select the Settings
icon from the top right.
Tap on Your Strava Subscription > Manage Your Subscription > Change Plan.
You will be prompted to select your subscription length.
Apple App Store
From the Strava app on iPhone:
Go to the You tab and select the Settings
icon from the top right.
Tap on Your Strava Subscription > Manage Your Subscription > Change Plan.
You will be prompted to select your subscription length.
Strava Website
Log in to your account and navigate to Settings in the menu under your picture in the upper right-hand corner.
Tap My Account in the menu on the left, then select Change Plan.
You will be prompted to select your subscription length.