You can try out all the programs in the VEGAS family for 30 days for free. Once the 30 day period has expired you can purchase the full version of a program without needing to reinstall it; simply activate the full version with the serial number supplied.
Even if you are an existing user of a previous version, a trial is highly recommended, to check compatibility with your system and to avoid disappointment in case you dislike any new features or restrictions.
Trial versions might overlay a watermark on rendered footage. Otherwise they are fully functional.