Can I use Complete Anatomy for iPhone without using Complete Anatomy 2018 on another platform?

Yes! With the upgrade for Complete Anatomy for iPhone, you have access to the full anatomical model, along with a large library of pre-prepared content from the 3D4Medical library. You can also choose to purchase and access Courses in the iPhone version.
To edit or annotate the model, to save content, and to create and share with groups, you will need the productivity version of Complete Anatomy, available on iPad, Mac, and Windows.