Speech therapy may be part of your life at different stages of your life. If you have a child with a developmental problem ( e.g. making age appropriate speech sounds, learning age appropriate language concepts), usually if the child is mature and motivated and the parents and support staff participate in homework and carryover activities, issues will resolve.
If you have a very very young child, you feel has speech and language developmental issues, consult with a speech therapist, who will design a program for you at home which she will monitor. These types of issues will resolve.
The case is different if you have a child with a diagnosis of a developmental disorder ( e.g. Autism, CP, Hearing Loss), or a communication order (such as stuttering or voice), or a syndrome ( such as Downs or Fragile X). a speech therapist may be a part of your family routine for extended periods of time.
Young adults may approach their speech problems differently then their parents. At a later age they may be more motivated and work to resolve any issues they may have had as children.
Older adults who suffer from stroke, or ALS, may need the consultation of a speech therapy to help them and their families cope with the changes in their speech, swallowing and feeding issues.