The full ledger: what continuing a novel with AI actually costs

The most useful number in this post is small. In our testing, one AI continuation on Foreverse’s official channel deducts about 19 credits. A credit is $0.0001, so that segment of story cost $0.0019 — call it a fifth of a cent. Everything else here is arithmetic on top of that number, because the question people actually type into a search box is “free AI story writer no subscription”, and the honest answer needs a ledger, not a slogan.

The shape of the answer up front: the app itself is free (importing, reading, branching — no rate limits, no trial clock), and generation is paid three ways. You start on granted credits, you can buy more by the pack, or you can plug in your own API key and pay the model provider directly. No route involves a monthly fee.

The three routes, one table

To make the totals comparable, assume a continuation lands around 400 words and a full “ride” — continuing a dropped or finished book until you are satisfied — runs 200,000 words, so roughly 500 continuations. That is a deliberately heavy scenario; most readers stop far earlier.

The routes are not exclusive. Credits and BYOK coexist per request, so the practical path for most people is left to right: burn the grant, buy one small pack, and only bother with keys if the volume justifies it.

How far do the free 5,000 credits go?

Signup grants 5,000 credits — $0.50 of face value, roughly 260 continuations at the measured 19-credit average. At 400 words each that is on the order of 100,000 words of generated story before you have paid anyone anything, which is enough to finish a novella- length ending or to properly audition the whole workflow on your own book. One honest caveat: 19 credits is an average, not a flat rate. Context length moves individual requests up or down, and heavier models bill more than lighter ones.

What do the credit packs cost?

Four pack sizes: $0.99 for 6,000 credits, $2.99 for 26,000, $9.99 for 90,000, $32.99 for 340,000. Per thousand credits that is $0.165, $0.115, $0.111, and $0.097 — the top pack is about 41% cheaper per credit than the smallest, but the smallest already buys ~315 continuations, so there is no real pressure to stockpile. Prepaid means prepaid: packs are bought manually, nothing auto-renews, and an idle month costs $0.

Here is the disclosure that makes the next section necessary. Official-channel pricing is the model’s official list price plus 50%, as a service fee — it covers payment processing, infrastructure, and the fact that you never have to create a provider account or manage a key. We print that number rather than bury it, because the entire case for the third route is that it routes around those 50 points.

When does BYOK win?

On unit price, immediately — on total cost, once your volume is steady. BYOK means bringing your own API key: register with a provider, top up there, paste the key into the app. Requests then go from your device straight to the provider at list price — Foreverse adds zero markup and stores the key encrypted on-device. There are 62 preset provider configurations, plus custom OpenAI-compatible endpoints; the BYOK page covers the mechanics and this explainer covers how to verify an app is doing BYOK honestly.

A worked example at real list prices. DeepSeek’s official pricing page (July 2026) lists deepseek-v4-flash at $0.14 per million input tokens on a cache miss, $0.0028 on a cache hit, and $0.28 per million output tokens. Take a continuation request with 10,000 input tokens, all missing the cache, and 800 output tokens: $0.0014 in, $0.0002 out — about $0.0016 per continuation, or $0.80 for the whole 500-continuation ride. And that is the pessimistic accounting: consecutive continuations reuse most of their context, cache hits bill at one-fiftieth of the miss price, so real chains land lower. Do not divide this number into the 19-credit figure directly — different accounting bases — but the direction is clear. Token prices have also been falling industry-wide for years; we wrote up the trend data separately.

The cost of those savings is friction: a provider account, a top-up, a key to keep safe, and a 401 error that is yours to diagnose. If you write a few segments a week, the difference between routes is measured in cents per month and the official channel is the right call. If you write every day across several books, a third off every request compounds into the only line item that matters.

Can you run this at actually $0?

Yes, with limits worth stating precisely. The app itself never bills — reading, importing, and branch management stay free — and the 5,000-credit grant funds about 260 continuations with no payment method involved. Past the grant, the $0 path runs through BYOK free tiers: several providers keep genuinely free API access at the low end, the best-known being Google’s Gemini API free tier, which still covers Flash-class models in 2026 (Pro-class went paid-only in April 2026) with daily request caps that reset on Pacific time and live quotas published per project rather than as a fixed table.

The honest fine print: free tiers cap requests per minute and per day, so a long evening session can hit a wall mid-chapter, and flash-class prose has a lower ceiling than flagship models. The workable pattern is a split: free tier for routine forward motion, a stronger paid model — switched per request — for the chapters you care about. Since every request logs its model and token counts in the app, you can audit exactly what the paid slice is costing you rather than estimating.

What does the same money buy on a subscription?

The prevailing shape in AI writing tools is the monthly plan. Sudowrite’s official pricing, to take the best-known example, starts its Hobby & Student tier at $19 per month billed monthly ($10 per month on annual billing) for 225,000 monthly credits — and on that tier, unused credits expire at the end of each cycle. For a working novelist drafting at volume inside Sudowrite’s toolset, that can be a perfectly rational buy; the credits fund heavy daily generation and the plan is the product.

A reader continuing books is a different consumption curve: bursty, small, and idle for weeks at a stretch. Against that curve the math stops being close. The entire 200,000-word ride costs about $1.10 in packs or $0.80 in BYOK tokens — less than one month of the cheapest subscription tier, with nothing renewing behind your back and no meter running while you are just reading. Twelve idle months on a $19 plan is $228; twelve idle months on prepaid credits is $0. The billing shape, more than any single price, is the argument.

Where the ledger stops: these figures cover text. Illustrations, narration, and video bill separately and cost meaningfully more per action, and your own model-shopping experiments are a line only you can estimate. But the core question — is there a way to do AI continuation without a monthly fee — closes cleanly. There is, three ways, and the most expensive of them costs about as much as a vending-machine snack per finished ride.