The three common pricing models
Credit-based cloud tools (such as Let's Enhance and VanceAI) give you a few free credits on signup, then charge per image via subscriptions or bundles. They're great for high volume but add up if you only need the occasional upscale.
Watermarked free tiers (common on mobile-first enhancers like Remini) let you try the tool but stamp the result, so you pay to get a clean image. Desktop licenses (such as Topaz Photo AI at a one-time ~$199) are powerful and offline, but they require an install and an up-front purchase.
When a low-cost plan beats a 'free' tier
For web images, social media, listings, and standard print, a browser-based upscaler that doesn't watermark output covers almost everything. You only need a heavier paid tool if you do high-volume batch work, very large-format print, or want offline RAW processing.
ImageUpscaler runs in the browser, upscales up to 10X, and never watermarks output. Plans start at $9/month and every plan is backed by a 30-day money-back guarantee — often cheaper in practice than 'free' tiers that force an upgrade to remove the watermark.
A note on fully free, no-signup options
There are truly free, open-source desktop options (like Upscayl) that have no watermark and no limits, which are excellent if you're comfortable installing software and have a capable GPU. The trade-off is setup and that everything runs locally. Browser tools trade that for instant, install-free access from any device.