Xubster (like most modern file hosts) does store premium status locally. Everything is checked on their servers. When you enter a “key”, their server validates it in real-time. If the key is not in their database as a legitimate, paid, unused voucher – it’s instantly rejected.
: Files start downloading immediately without the mandatory 30-second countdown or "human verification" interruptions. xubster premium key upd
Updating to a valid premium key unlocks the following core features: Xubster (like most modern file hosts) does store