Upgrade to Dilly
Pick Dilly in Settings -> Plan -> Manage subscription or complete checkout via a parent-sponsored link. Stripe charges the prorated difference and unlocks 150 tokens per month and Chat immediately.
Downgrade to Starter
Pick Starter or cancel the Dilly subscription. Dilly plan features continue until the renewal date, then the account moves to Starter (8 tokens per week, no Chat).
Cancel entirely
Cancel from Settings -> Plan -> Manage subscription (Stripe customer portal). Paid features remain until the cycle ends. Subscriptions will not appear in iOS Settings, Subscriptions, because Apple is not the biller.