From first stage onwards how long need to use medicine for parkinson's disease? is it not curable?

Parkinson's disease is not curable, but can be controlled with medication. The most common is Carbidopa-levodopa, orally, inhaled, or infused. Also MAO B inhibitors, and other numerous medications are available. Your doctor will prescribe what is best, but these medications won't cure you, only help you to function as best as possible.

If you do have Parkinson's Disease, you will need to address this for the rest of your lifetime. Early on, most neurologists will prefer dopamine agonists over the first 2-3 years, but sooner or later L-DOPA will be instituted. Eventually, Deep Brain Stimulation could be considered, especially in younger patients. Work with a neurologist who is a Movement Disorder Specialist.