Short answer: plan changes aren’t supported inside the ElevenLabs iOS/Android app, and if your current subscription was started via the App Store/Google Play it’s managed by those stores, not by ElevenLabs.
What to do
If you’re using the native app: open a browser and upgrade on the website (elevenlabs.io). Your subscription works across web, iOS and Android once purchased. (help.elevenlabs.io)
If you originally subscribed via the mobile app (Apple/Google): cancel the in‑app subscription in your App Store/Play Store account, wait for it to expire, then subscribe to the Starter plan on the website. You can’t upgrade on the website while an in‑app subscription is still active. (help.elevenlabs.io)
References
Managing Your ElevenLabs Subscription (Mobile App vs. Website). (help.elevenlabs.io)
How do credits work on the ElevenLabs iOS or Android app? (notes that you can log in on the web to upgrade and use your subscription across web and mobile). (help.elevenlabs.io)
worthy sierra
cyan tide