As you battle other Mechadroids, you'll slowly gain experience points (XP). Once you have accumulated enough XP for your current level, you'll be given 5 attribute points (AP), which you can use to upgrade various attributes (see the attributes page for more info). Once you have upgraded your Mechadroid, your Mechadroid's level will increase and you'll need to start accumulating more XP before you are rewarded more AP.