Don't trust the free VPS providers except some few really big ones
I have not used free VPS before, because there was none. However, I have tried one over the last month, only to find out that they are liars and scammers.
One of them is the evolution-host.com. They told me that I can use their free service unless I put a link in my website, and choose to go to their designated link and put some comments there every month, when the subscription is due. The commenting will takes less than 30 seconds, as they promised me. Therefore I consider it not a big deal and decided to continue with their free VPS. However, yesterday they sent me an notification that asked me to pay a USD 20 monthly fee if I want to continue with their service. In conclusion, they only provide you with an one month free trial, while during that one month period, my site has helped greatly in promoting their service, because my site has a quite significant traffic and is well known in the industry. They have gained enough popularity and exposure owing to my promotion, therefore they think it's no more useful to let me enjoy their free VPS. And I have to look for new service provider which took me a whole night last night. As a whole, I have gained nothing from this one month period, because I have a paid service which will only expire a week later, while evolution-host has acquired some fame due to my linkage.
Another free VPS provider, euserv.com, is offering you very bad experiences. It's hard to ssh login, and it's very hard to perform commands while logged in. And finally it gave me the following message after some operations:
Connection closing...Socket close.
Connection closed by foreign host.
Disconnected from remote host(euserv) at 09:33:37.
And then I can never login again, and I have to reinstall the system to resume my access. In this case all what I have done before are lost.
My suggestions to all people seeking free VPS here: never try them at all. All are fake, scammers. Don't waste your time. You can get your hosting in many other ways, such as free shared hosting, free PAAS etc, but no free VPS. There are only two things which don't give out free on the web: domains and VPS.