You can search google for anything you want as many times as you want.
Google doesn't limit you to any amount of web searches you can do on their search engine but if you do search too many things in a short amount of time you may get a message stating unusual activity from your IP address.
But all you have to do is acknowledge that you're not a bot and you can continue to search from that IP address and computer.
It's just a system put in place so that Googles servers aren't affected should a bot try to take them down by overloading servers.