The version you are about to download is the free version. It is not a free trial in the strictest sense, it is more of a stripped down version of the full program. The developers have purposefully made the free version inconvenient in order to prompt you into buying the larger/full version. For example, the free version limits how many words you may check at a time, which means you have to split larger documents into smaller pieces if you wish to check them with this plagiarism detector.