Can a company renew a contract without notice?

Yes, if the contract contains an auto-renewal clause, it renews without any new notice, because you already agreed to that mechanism when you signed. That's the entire design of evergreen clauses: silence equals consent. The notice obligation usually runs the other way: it's on YOU to give notice within a defined window if you want to stop the renewal.

Limits exist: many jurisdictions require businesses to remind consumers before auto-renewing (and regulators are tightening this), but B2B contracts mostly enforce as written. Some contracts also require the renewing party to confirm new pricing; check whether price changes at renewal need your consent or just notification.

Defense is straightforward: know which of your contracts are evergreen, record each one's notice deadline, and put a reminder far enough ahead of it to actually evaluate before the window closes.