副本次数增购：耗尽后的付费增购

local function enter(actor)
    setplayvar(actor, "RUNS", getplayvar(actor, "RUNS") - 1)   -- 无限扣，负数次
end

local FREE, BUY_MAX, PRICE = 3, 2, 200
local used, buys = 0, 0
local function enter(actor)
    local total = FREE + buys
    if used >= total then
        if buys >= BUY_MAX then
            sendmsg(actor, 1, "今日次数已用完")
            return
        end
        takeitem(actor, "金元", PRICE, 0, "增购副本")
        buys = buys + 1             -- 增购上限锁定
    end
    used = used + 1
    sendmsg(actor, 1, "进入副本 " .. used .. "/" .. total)
end