Teensafe? Does it work if he deletes the message?

I want to install teensafe iphone monitoring software on my sons iphone and have two questions. I understand it works by getting the info from my child's iphone backup to iCloud but does that mean if he deletes the message before the backup, I will not be able to see it?

And how much does it cost because the prices don't seem apparent…

No, the software will save the information even if the message is deleted, making it avaliable to you. However be warned that 265bit SSL is far from secure. Breaking this kind of connection is childs-play and Installing this kind of software opens a backdoor to your childs phone giving all kinds of malicious hackers access to everything they see and do as well as you.
I can't find pricing but read throuh there terms before installing/investing. Particularly the no refunds & immidiate charge at end of trial period section (6) here: http://budgetingandplanningsoftware.com/helps/terms

How to recover my childs deleted text messages