You will never have to buy another starter again if you treat it right. However, no one strain of starter is the same and can have their very own unique flavor.
Feeding your starter will help it grow to be the size you need it. It only takes, roughly, 50g of starter to bake one loaf of bread.
Example: If you feed your starter so it is, at least, 100g, you can take half of that to bake bread, and during feeding time, you will build it back up to 100g or more.
