Anti-Theft Device Activated or Not?

I successfully installed Avast mobile security onto my Samsung Galaxy smartphone the tried to activate the Anti-Theft device. I gave it a PIN which it accepted ,and a gmail email address, as well as another mobile phone number.

All OK, but what has this given me? As it is, anyone could take my phone and use it. They do not even need a password to open it. They could top up the prepaid SIM card just as I do and use it indefinitely.

Perhaps without my PIN, Avast would prevent them from using another SIM card with that device – but I thought the whole point was that I could shut down the phone from my computer straightaway.
How is this done?
Am I supposed to use the email address I gave to Avast to send an email to Avast??

Hello,

I’m afraid you misunderstood what our apps are about. Please take a look at our product at

http://www.avast.com/free-mobile-security

to find out more about Anti-Theft and Mobile Security.

Regards,

Werner