What does maximum limit of applications reached on lg cookie mean?

I was having this same issue and was driving me insane I would try to do something and it wouldn't let me, I tried just ending all apps or things I had open but that didn't work….I never turned my phone off before and then I read somewhere that this was caused by the internal computer having background apps running that you can't turn off…so anyway…i have started to turn my phone off in the night time before I plug it in, and for the last month I have not received that error at all!! I guess shutting the phone off releases all those stored apps running in the background.