Protea comes in two editions: the free regular edition, and the purchasable Laurel Edition.
The free version contains the full story and all available h-scenes, so you do not miss out on anything important by not purchasing the Laurel Edition. Only purchase the Laurel Edition if you want the extras or feel like supporting the development of future similar visual novels!
The extras include:
-Developer commentary on various topics relevant to the story and development of the visual novel.
-Full CG Set
-Full Sprite Set
-Protea's Original Soundtrack
-Unarchived Ren'Py Scripts