Plugin active in just one category?

This functionality is available in the PRO Version. You need to select the category from the setting called Allow Selected Categories.

Please note that this will still allow the voting for a post which is combinedly assigned to other categories as well. I mean if a post is assigned to 2 categories and your selected category is one of them, then the voting will still be allowed even though you have allowed this for only one of those 2 categories so do not think that this is not working. If you restrict the posts to single category, then you will not find this misleading.

For more queries on the PRO Version, please use our support forum here.