The gate
4K output requires an active subscription — Starter ($9.90/mo), Pro ($19.90/mo), or Premium ($49.90/mo). Credit packs alone do not unlock 4K, and there is no per-image 4K purchase. 1K and 2K stay open to every account, including free ones.
What happens after you subscribe
The 4K option in the resolution picker unlocks immediately while your subscription is active. Each 4K image then costs 8 credits (vs 1 for 1K, 3 for 2K), billed from your subscription credits first. If the subscription lapses, 4K locks again — your already-downloaded 4K images are of course unaffected.
When 4K is worth it
Print, hero banners, and zoom-on-hover product viewers. For everything else, proof at 1K and finish at 2K — the resolution guide has the full cost math.