My friend has cerebral palsy, how do I know if he still has it?

Still has it. Cerebral palsy is due to a brain injury sustained before age two. The brain injury is stable, but the manifestations of the injury can change. Once you have been diagnosed with cp, you always have it.
He does. Cerebral palsy is generally a lifelong, chronic condition although manifestations can change over time. Children with CP grow, develop and gain new skills over time. Also, it is important to know that CP is a neurological disorder and is not contagious.