Will I be charged?

I have the Moto Q9m and I only use that phone for calling and texting because I don't need the other features yet. I don't use the internet and I blocked it so my Moto Q9M doesn't open it by itself. I chose the Pay Per KB ($0.00) because I didn't want to pay $44.00 a month for something that I won't even use a lot. Will I be charged for the memory usage on my PDA? or will I only be charged if I actually use the internet?