no warning session is almost over Basic Plus subscription

Hi, 
In my Basic Plus subscription I do not receive a warning that the 40 minutes are almost over. I can't know up front whether I need more than 40 minutes. When I had a free account there always were a couple of warnings, but now I see none. This is very frustrating, because I'm thrown out every time without having a option to choose wether to use one of my 4 prolongation or not. I haven't been able to use them up till now!
So... why no warning?

Thank you.