wrap like this:
if limit("Aegis_notification", 5) then
send("gt one minute left on my aegis!")
end

function limit(cmd, seconds)
  local cts = getEpoch()

  if cmd_limit == nil then
    cmd_limit = {}
  end

  local cok = 0
  if cmd_limit[cmd] == nil then
    cok = 1
  else
    local cdiff = cts - cmd_limit[cmd]
    if cdiff > seconds then
      cok = 1
    end
  end

  if cok == 0 then
    return false
  end

  cmd_limit[cmd] = cts
  return true
end