What advertising network is this? I encounter this type of pop-up ad often when using an app on iOS. What advertising network is serving this advert? (Or how would I determine this in general when the ad cycles to another app)
Depending on how terminal savvy you are.. you might look into sleuthing around using lsof and netstat. 

This will only work with a jailbroken iOS device. Install the packages network-cmds and lsof using Cydia. 

Close all your other applications, except for the one generating the ad. Then, open a Terminal, run one of these commands and look through the list. Simply use the process of elimination to figure out which IP address it is talking to. (IE: if you know you are running Spotify for music, you could rule out any active connections that are going to a website with "spotify" in the hostname.) After narrowing it down, if you are left with a set of IP addresses instead of hostnames, you could try running the remaining ones through an IP address lookup webpage.

Here are the commands. I've supplied a little bit of sample output from my mac to show you what I get. These are the same commands in the packages above for iOS, so you should get equivalent output. Be warned, you will get a lot of output, so be prepared to scroll.

[MacBook-Pro:~] jonathan% lsof -i

COMMAND    PID              USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
UserEvent  228 jonathan    6u  IPv4 &lt;MAC&gt;      0t0  UDP *:*
Mail       240 jonathan   34u  IPv4 &lt;MAC&gt;      0t0  TCP 192.168.1.124:49590-&gt;17.158.8.25:imaps (ESTABLISHED)
Mail       240 jonathan   37u  IPv4 &lt;MAC&gt;      0t0  TCP 192.168.1.124:49533-&gt;17.158.8.25:imaps (ESTABLISHED)


OR try

[MacBook-Pro:~] jonathan % sudo netstat
Active Internet connections  
Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)
tcp4       0      0  192.168.1.124.50428    cache.google.com.https ESTABLISHED
tcp4       0      0  192.168.1.124.50427    cache.google.com.https ESTABLISHED


Where 192.168.1.124 will be your local IP address instead of what is shown above.