Making Server

You realize that 50 players does't only rely on RAM, right? If you have plugins that tick a lot you will need a good processor. 50 people on two gigs of RAM is going to depend on what plugins you are using. Also, is this a dedicated server? If so, the operating system uses RAM, so you will have less RAM in reality.

BUMP....

I want to have plugins like economy,home,warp,shops etc. and so how many people can be with that plugins?

Yes like said 50 players on a 2gb will depend on how many plugins you have installed and the size of these plugins, and also how many worlds you require.. i think if you keep it simple you should be fine.

Just think about how much data needs to upload through the pipe at once per player! More memory speeds this process and will save lag.. just chop and change things around and get the right balance..

ohh and good luck finding 50 players! I wish i could

50 might be a little to much for 2gb.. It also depends on the plugins you have, and btw it gives you a estimate on the site when looking..