FreeContentStream is a Boolean property that indicates if the object instance can free the TStream resource allocated in ContentStream. 

FreeContentStream is set to True in the Create constructor, and ensures that ContentStream will be released, if assigned, prior to retrieving an HTTP response in the Destroy method. 

Under normal circumstances, FreeContentStream is not changed during the lifetime of the HTTP response. Set FreeContentStream to False when ContentStream is assigned manually, and the stream must continue to exist even after destruction of the HTTP response.

TIdHTTP 

ContentStream 

Create 

Destroy