[iceeedr]

I wrote by phone, that is, not tested and there may be errors.

PHP Code:

#include <amxmodx>

new bool:UserMsg[33]

new AdsCvar, AdsHandler
public plugin_init()
{
    register_clcmd("say /messagestop", "MsgHandler")
    AdsCvar = register_cvar("ads_time", "40")
}

public client_putinserver(id)
{
    if(!is_user_bot(id))
    {
        AdsHandler = get_pcvar_num(AdsCvar)
        UserMsg[id] = true
        CountDown(id)
    }
}

public CountDown(id)
{
    if(!UserMsg[id]) return 
    
    AdsHandler --
    
    if(AdsHandler > 0)
    {
        set_hudmessage(0, 0, 255, -1.0, 0.29, 0, 6.0, 40.0);
        show_hudmessage(id, "Welcom To Public Server^nAds: xxxx^nxxxxxx^nxxxxxx")
        set_task(1.0, "CountDown", id)
    }
    else
    {
        remove_task(id)
    }
}

public MsgHandler(id)
{
    UserMsg[id] = false
    
    client_print(id, print_chat, "You %s the ads.", UserMsg[id] ? "enable" : "disable")
    return PLUGIN_HANDLED
}