Onyx has several plans so you pay only for what you need. The always‑current price is on the pricing page; there you see each plan with its amount and what it includes.
You can pay month to month or yearly. The yearly plan is cheaper than paying 12 separate months.
You can create your account for free and try Onyx before subscribing. When you want more accounts or features, you upgrade.
You do it from My account → Subscription. Upgrading is immediate. Downgrading applies at the end of the period you already paid: you do not lose what you paid and you keep the features until it ends.
Onyx Trading Live