First connect to your CentOS VPS using an SSH client like Putty.
Enter the command: free -m
This will show you in megabytes (mb) how much memory you have, how much is used and how much is available.
Remember 1024mb is equal to 1gb of memory.
It's important to not run out of memory.
If you think you are running out of memory but aren't certain, please contact InfoQuest support and we can confirm this for you.