The flat-fee era for AI tools is quietly ending

The all-you-can-eat subscription is giving way to usage-based billing, and the jump is brutal when a heavy reasoning model does the work a flat fee used to hide — one developer reported going from about $29 to $750 a month. Two moves this week if you build with AI: instrument your token usage so you can see where the spend actually goes, and test whether a cheaper open-weight model covers your routine eighty per cent. Keep the expensive model for the hard twenty. The teams that get burned are the ones who find out their costs at the invoice, not the dashboard.