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]
(..) - COUNT ODO: I am right. And Roland can confirm it. I believe we can no more trust him than trust a wild boar. In any case, Your Highness, he has now served his purpose. Then? Then you must use your power and proceed quickly. Arrest Rollo before he can savor and celebrate his triumph. (..)2016 TvShow: Vikings Title: Portage Season: 4 Episode 8