The free versions of the courses in most cases are limited to watching instructional videos. At the same time, the registration of access to the paid class allows you to pass the exam and if the completion of the exam is rated at a passing score or higher, then the student receives a certificate and becomes a licensed plumber. This document is not a career diploma, but it definitely acts as a competitive advantage in the career development of plumbers who search the work over those who do not have this certification. Moreover, some courses are compiled as individual courses. This allows students to choose topics for passing and deadlines for completing tasks and follow these fixtures. This feature is not available in the free version of the educational class.