Getting licensed is necessary for real estate brokers and sales agents. To obtain a license, applicants must be at least 18 years old, a high school graduate and pass a written test. In most states, construction executives need between 30 and 90 hours of classroom instruction. Brokers usually must have one to three years' experience selling real estate. Licenses must be renewed every year or two, but a renewal exam usually isn't required. As transaction become increasingly complex, college diplomas are becoming more favored.