Android phone help!!!?

ok soy i recently got my new Samsung galaxy prevail, and noticed it only had 126mb internal memory, then after downloading 3 apps;(Facebook, Score Mobile, and Score Mobile FC) i had 116mb. Then when I began using the apps for a while, I noticed my memory when to 110mb. Do apps use memory when used? I even tried going to settings and clearing all data for the apps, but it only added +2mb. Does that mean when i run out of memory, that i will not e able to use the internet, or use the apps,or talk and text, please help.