Free plan limits
The free plan caps things like queue duration, guests per queue, and number of active queues. When you're close to a limit, you'll see a banner on your dashboard letting you know.
Upgrading to Premium
Premium removes these caps — unlimited queue duration, guests, and queues. You can upgrade any time from the upgrade prompt on your dashboard or from Settings → Subscription.
Managing your subscription
Your current plan, renewal date, and billing details live under Settings → Subscription. From there you can also cancel — your plan stays active until the end of the current billing period, after which you're moved back to the free plan.