on most servers i visit i get disconnected, sometimes i don't. Is this a trial version restriction, a bug, or am i just getting kicked?

try more servers, not the same ones over and over. If it still happens, it is either something wrong with your internet connection or computer, or a bug in the server software (though a bug is not likely to cause this)

Check internet connection and computer. It would tell you if you where kicked.

You shud give us more info, maybe u get ping kicked or kicked from console sometimes and yea try diiferent servers just like flab said