how to tell if Skype is active

[barber76]

Hi everyone.
I'm running WP 8 on Lumia 521. When I tap 'back' button I only see 4 most recent apps. Meanwhile, often I have Skype left running (and it drains battery like crazy), and it is not in the list of 4 recent apps. Is there an easy way to see if Skype is active on the phone?
Thanks.
Edit: I'm wrong about only 4 recent apps. There're more. But the point stays that Skype, while running, is being left out of the list.

 

[AmGaD-SaLaH]

That's smart question.. I hope someone knows the answer for that