She knew from a young age that her sole 'purpose' (in life) was to be a writer. [=she knew that all she wanted (in life) was to be a writer]
We were happy to know that the money was being used 'for a good purpose'. [=for something useful, important, etc.]
There's little/no 'purpose' in restarting the process. [=there is little/no reason to start the process again]
(..) Why do you have to defend her? I thought it was funny. Forget it. Hey, John, we gotta go. Oh. Yeah. Did you ever wonder what your purpose in life is? This book is about finding your soul's purpose or destiny. Every soul has its path, but sometimes that path is not clear. (..)2003 Lost in Translation