Downgrading to a lower plan
If you purchase a paid iRefer plan and then downgrade to a lower plan, iRefer only charges you a prorated amount the next time you are billed for your new plan.
Canceling before auto-renewal
When you cancel your subscription to avoid auto-renewal, that change is effective immediately. If you want to turn off auto-renewal so that you don’t get charged again but can still use your plan until it expires.