The rules behind the tiers above
VIP comes in three tiers — Bronze, Silver and Gold — each granting a bonus to experience and item drop rate for a fixed number of days. It's purchased by spending Rex Points already on the account, and everything shown in the tiers above pulls from the account's real state once you're logged in.
Nothing sold here grants a stat, a weapon or any advantage a free player can't reach by playing — VIP only affects the pace of progress through its experience and drop bonuses, never combat power directly. That's the same rule the rest of the server runs on.
Buying a VIP tier while one is already active overwrites the current expiration with the new tier's full duration — it doesn't add days on top of what's left. The purchase screen always previews the resulting expiration date before you confirm, so there are no surprises.