Free data is fine, if all you’re interested in is the latest price of a stock. But if you wish to run your data through a charting package, and make real use of it, you need to maintain it. For instance, you need to adjust it for capital re-constructions.
In the case of the ASX, about six stocks need to be adjusted on average per week. A further dozen will have been de-listed by the exchange or had a name or code change. In addition, new stocks that come on board need to be identified.
Premium Data handles all of these maintenance acvities, and others, automatically, as part of database maintenance.