For running Expert Advisors in general, you need VPS and your objective when choosing a VPS is to keep the RAM of your VPS at 30% maximum as the market volatility spikes at the time of critical news which consumes RAM and Processor for exchanging huge data in and out.
You need higher VPS specs when using MT5. And for Investment Castle EAs on MT5; 1 EA on 1 chart comsumes around 300 kb of RAM.
So for 4 GB RAM VPS, you will can run 12 charts but monitor the performance of your VPS during critical news.
I recommend this VPS provider for their low latency and price models, this is the most cost effective VPS provider.
Here is a topic about Chocoping VPS provider.