Its depends on your requirement, how many MT4 you want to keep open in your VPS. Generally, it will be better if you allocate 500 MB for per MT4/MT5 software so if you want to keep open 5 MT4 then you need to have 2000 MB or 2 GB RAM VPS. That means you need to go for the BASIC package with 2 GB RAM. If you want more consultation then please contact our support team.