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]
(..) if I wanted to. My funds are in Liverpool, not in Atlanta. If I tried drawing a draft, the Yankees'd be on me like a duck on a June bug. So you see, my dear, you've abased yourself to no purpose. Here, here, here, stop it! Want the Yankees to see you like this? Take your hands off me, you skunk. (..)1939 Gone with the Wind