Checking images is always free and unlimited. You only count images you protect: the copy saved with the notice and recorded in the ledger.
Going over is fine: extra images are billed per 1,000 (Studio $2.90, Business $1.99, Enterprise $0.50) and you're warned at 80%. One licence works in the Photoshop panel now, and in the Mac and Windows apps as they launch; it isn't tied to a Photoshop seat. Your photos never leave your devices: only the licence key and counts are sent. Paid licences follow the Company Licence Agreement.
Bitphoto writes a machine-readable "no AI training" notice into your images. It's a label, not a lock: it doesn't stop copying, screenshots or AI training.