After installing AdminExile Pro 3.13 and enabling the IP Security feature I clicked on the + sign for whitelisting IPs just to see how it works. I forgot about it and left it as it was with blank fields. After configuring other features the plugin wouldn't allow me to save or save&exit. The thing is that in my case the plugin displayed a pink rectangle that probably should contain the warning message with regards to the empty fields, but it was empty showing only a misplaced x button to close it. Not sure what kind of message should be there (and maybe it's just some sort of browser rendering bug on my end), but after removing the empty entry field I'm able to save & close.
Also, on your site, when I try to cancel the recurring payment in "My Subscriptions" section I get this message:
There was an error while cancelling your subscription. Please contact the site administrator."