Registering Bandicam with an email and serial number is essential to unlock its full features and benefits. The free trial version has limitations, such as adding a watermark to the recorded videos and limiting the recording time. By registering the software, users can remove these limitations and enjoy features like high-quality video recording, customizable settings, and priority customer support. Moreover, registration allows users to receive updates and new features, ensuring they have the latest and greatest version of the software.