Regard the nexus as your MB allowance for game play, then 500 would be pretty steep, especially if you still have a great deal of development to do....the
question is then raised....how optimized is your project to require such a demand?

You can gain a measure by using the F11 key to read the debug panel and make such determinations....

I'm guessing you have lots of entities and large texture maps at the moment so take some time to analyze your asset deployment...