Yes you can, in different ways.
You can disallow votes on frontend or to a specific Joomla user group. To disallow frontend voting, set frontend voting to Off in the criteria.
To limit voting on particular user group, use the general options.
We have detected that you came here from a website that distribute non official sources of our extensions. As we care about all our users, including hackers :) we want to warn you before you do something you will regret.
Is it worth it using nulled extensions? Well we don't think so, it’s a real problem for many reasons: