Terms of Service
Last updated 3 October 2026.
Who this is
Chess Mastery Trainer is made and sold by StratumCode ("we", "us"). These terms cover the Chess Mastery Trainer desktop app for Mac and Windows and this website. Using either means you agree to them. Questions about anything here go to sales@chessmasterytrainer.com.
The trial and the purchase
The app is free to download and runs fully for 15 days -- no credit card, no account, no limited features. After the trial, a licence key keeps it working. A licence key is a single payment of $34.99, once, through PayPal. There is no subscription and no recurring charge of any kind: you pay once and the key keeps working for as long as you keep using the app, including for all future updates we release, at no extra charge.
One licence key covers one buyer, for their own use, on both the Mac and Windows builds -- you don't need to buy it twice if you use both. The key is checked by the app itself, on your own machine, against the email address you bought with; the app never contacts us to check it, and we have no way of knowing when or how often you use it. Because of that, we also have no way of stopping a key being shared or reused beyond one person -- we're relying on buyers using this honestly, the same basis the trial itself runs on.
We don't offer refunds on a completed purchase. The 15-day trial is there specifically so you can decide the app is right for you before paying anything -- if you're not sure, that's what it's for. If something's genuinely gone wrong with a purchase (a duplicate charge, a payment that didn't go through correctly), email sales@chessmasterytrainer.com and we'll sort it out.
What you can't do
The licence key and the installer are for your own use. You can't resell, redistribute, or publish the app, the installer, or a licence key, or present the app as your own work. You can't try to work around the trial period or the licence check.
Third-party components
The app bundles the Stockfish chess engine and, optionally, Maia-3 or Leela Chess Zero as separate programs, and uses puzzles from the Lichess puzzle database. Full details and licences are in the footer of this site. Chess Mastery Trainer is not affiliated with Lichess, Chess.com, Stockfish, Hugging Face, or the Maia project.
Checkout is handled entirely by PayPal under PayPal's own terms -- we never see or store your card or PayPal account details.
No warranty
The app is provided as it is, without warranty of any kind, express or implied, including any warranty of fitness for a particular purpose. We don't guarantee the app is free of bugs or that it will meet your particular needs. To the fullest extent the law allows, we're not liable for any indirect, incidental, or consequential loss arising from using or being unable to use the app; our total liability for anything related to the app or a purchase is capped at what you actually paid for it.
Changes
We may update these terms from time to time; the date at the top of this page always shows the version currently in effect. Continuing to use the app or this site after a change means you accept the update.
Governing law
These terms are governed by the laws of the Philippines.