Recently they changed from a reasonable one-time purchase model to a mostly subscription model. There is still a one-time purchase option but it's incredibly expensive at $199.99, and an upcoming iOS update is somewhat Sherlocking the broad field of OCR apps by automatically performing OCR on images displayed in native apps.
Free CamScanner accounts have access to 200 MB of free storage space. 10 GB storage space is available for full version license (monthly subscription).