Freemium blends free and premium: the core product costs nothing, and revenue comes from users who upgrade for more. The free tier is not a trial that expires; it is meant to be genuinely useful on its own, so people can adopt the product and build a habit before any money changes hands. Done well, that habit is what makes the eventual upgrade feel easy.
The model works when the free tier is good enough to attract a large audience yet bounded enough to leave a clear reason to pay. Common walls are usage limits, seats for a team, advanced features, or removing branding. The art is placing that wall where upgrading feels like a natural next step rather than a penalty.
The economics are unforgiving if the ratio is off. Free users still cost money to serve, so a tiny fraction converting to paid has to cover everyone. Founders often underestimate that support, hosting, and especially AI inference costs pile up on free accounts, quietly eroding the margin the paid tier is supposed to protect. Model the conversion math before launch, not after.
Freemium fits products with low marginal cost per user and natural word-of-mouth, where the free tier doubles as marketing. It fits poorly when serving each user is expensive, which is a real tension for AI tools whose every free action burns inference. Watch conversion rate and cost-to-serve together, not either one alone.