Legal
End User Licence Agreement
Version 1.0 · 28 September 2026 · Applies to the ShiftMask desktop application
This agreement covers your use of the software. It does not cover your purchase: ShiftMask is sold through Lemon Squeezy acting as merchant of record, and the terms of that sale — payment, refunds and your right of withdrawal — are theirs. Our refund policy is answered in the FAQ.
This Agreement is between you and 4optima Sp. z o.o., ul. Wydmowa 4, 05-092 Łomianki, Poland (KRS 0000544621, NIP 1182105589), which develops and publishes ShiftMask (“we”, “us”).
By installing or using ShiftMask, you accept this Agreement. If you do not accept it, do not install it. The application shows you this text on first run and asks you to accept it there; a Polish translation is included in the application for convenience, and this English version is the one that governs.
1. What you may do
We grant you a perpetual, non-exclusive, non-transferable licence to install and use one copy of ShiftMask on one computer, for any purpose, personal or commercial, including work you do for your clients.
There is no limit on how much you use it: no cap on files, rows, projects or output, and no expiry. A licence with an expiry date is a trial licence and says so on the activation screen.
You may install it on a replacement computer. The licence follows you, not the hardware — see section 4.
2. What you may not do
- Use one licence on more than one computer at the same time.
- Share, resell, sublicense, rent or publish your licence token.
- Remove or alter the licence mechanism, or use ShiftMask without a valid licence.
- Reverse engineer, decompile or disassemble the software, except where and to the extent that applicable law gives you that right regardless of this Agreement — in particular for interoperability purposes. If you intend to rely on that right, we ask that you contact us first: it is usually faster for both of us if we simply tell you what you need to know.
3. Your data
ShiftMask runs entirely on your computer. It does not send your data anywhere, does not require an account, and contains no telemetry. We never receive, see or store the files you process, and we could not produce them if we were asked to.
What the website and the purchase collect is described separately in our Privacy Policy.
4. Licences, and moving to a new computer
Your licence token is tied to the device identifier shown on the activation screen. Verification happens entirely on your machine — there is no licence server and no check-in.
When you replace your computer, write to us and we will issue a new token. There is no charge and no limit on how many times. We ask that you stop using the licence on the old machine.
Because activation is offline, a token cannot be revoked once issued. That is the cost of working on machines with no internet, and we accept it deliberately.
5. Updates
Your purchase includes every update we release in the twelve months after the date of purchase. After that the version you have continues to work — indefinitely, offline, without reactivation. Renewing for a further year of updates is optional.
We may change, add or remove features in an update. We will not change an update in a way that disables software you have already paid for.
6. The vault, and the password you must not lose
ShiftMask keeps the map between your real values and their stand-ins in an encrypted vault on your computer, protected by a password that you choose and that only you know.
If you lose that password, the vault cannot be opened — by you, by us, or by anyone. There is no recovery procedure, no master key and no support route that changes this. It is a property of the encryption, not a gap in the product: a recovery route for us would be a recovery route for anyone who obtained the file.
Everything that depended on that vault is lost with it, including masked exports you produced earlier. Back the vault up, and keep the password where your organisation keeps its other critical secrets.
7. No warranty
ShiftMask is provided as is. We do not warrant that it is free of defects, that it will run on every configuration, or that its output will be fit for any particular purpose of yours.
In particular: ShiftMask masks and pseudonymises your data. It does not anonymise it. The map back to the real values is retained, which under the GDPR means the masked copy remains personal data. Deciding what you may lawfully do with that copy — including whether you may give it to a particular AI service — is your decision and your responsibility, and depends on your own obligations, not on ours. Verify the output before you share it.
8. Liability
Our total liability to you under this Agreement is limited to the amount you paid for your licence.
This limit does not apply to liability we cannot lawfully limit — in particular damage caused intentionally or by gross negligence, and injury to life, body or health. Nothing in this Agreement excludes or limits the rights you have as a consumer under the mandatory law of the country where you live.
9. Other people's software
ShiftMask includes open source components licensed by their own authors. Their licence terms and copyright notices are in the file THIRD-PARTY-NOTICES.txt, distributed with the application, and they govern those components rather than this Agreement.
ShiftMask uses the Microsoft Edge WebView2 Runtime, which is Microsoft's software and subject to Microsoft's own terms. It is not part of what we license to you.
10. Ending this Agreement
This licence ends automatically if you materially breach section 2 and do not put it right within 30 days of us asking you to. You may end it at any time by uninstalling ShiftMask.
Sections 3, 6, 7, 8 and 9 survive the end of this Agreement.
11. Law and disputes
This Agreement is governed by Polish law. If you are a consumer, this does not deprive you of the protection of the mandatory rules of the country where you habitually reside, and you may bring proceedings in your own courts.
If you are not a consumer, disputes go to the courts having jurisdiction over our registered office.
12. Changes
This version applies to the copy you install. If we change this Agreement, the new version applies to versions of the software released afterwards — not retroactively to the licence you already hold.
Contact
4optima Sp. z o.o., ul. Wydmowa 4, 05-092 Łomianki, Poland
shiftmask@4optima.pl · Full registration details