Sell a plugin with a license

OADM has a license check for plugins you sell. You don’t need a license server or your own license code: you sign a license key for each customer, OADM checks it offline, and your plugin asks OADM whether it may run.

Plugins under the Apache 2.0 license of OADM may be closed source and sold; nothing has to be published.

How it works

1. Every OADM server has a server ID, made at its first start. The customer finds it on the Settings page (and on the Plugins page while a plugin needs a license) and sends it to you. A restored backup keeps it, so moving a server keeps its licenses.
2. You make a key pair once. The public key goes into your plugin’s project (and from there into its plugin.json); the private key stays with you.
3. For each sale you sign a license key for the customer’s server ID: who it is for, until when and, if you want, which features.
4. The customer pastes the key on the Plugins page. OADM checks the signature with the public key of your plugin.json, the plugin id, the server ID and the date.
5. Your plugin reads the result and decides what runs.

OADM is open source, so someone determined can always remove a check. The license keeps honest customers honest, which is what most commercial plugins need.

1. Make your keys

dotnet oadm license keys --out ../acme-keys

This writes private-key.pem (keep it secret and back it up: it signs every license) and public-key.txt, and prints the properties for your project. It never overwrites a key: a new key would make every license you sold invalid. In a checkout of OADM the same command is manage license keys.

2. Declare the license in the project

In the server part’s project file:

<PropertyGroup>
  <OadmPluginId>acme.site-reports</OadmPluginId>
  <OadmLicensePublicKey>MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE...</OadmLicensePublicKey>
  <OadmLicenseFeatures>reports;export</OadmLicenseFeatures>
  <OadmLicenseTrialDays>30</OadmLicenseTrialDays>
</PropertyGroup>

Property	Meaning
OadmLicensePublicKey	Your public key from oadm license keys
OadmLicenseFeatures	The features a license can unlock, separated by ; (shown on the Plugins page, optional)
OadmLicenseTrialDays	Days the plugin runs without a license, from the day the server first loaded it; 0 or missing = no trial

The build writes them into plugin.json as its license entry (publicKey, features, trialDays); with a plugin.json of your own, write the entry there. Without a public key the plugin is free and OADM asks for nothing.

3. Sign a license

dotnet oadm license sign --key ../acme-keys/private-key.pem --plugin acme.site-reports
    --server 7f3c2a1e-5b8d-4c6f-9a2e-1d0b4e8f6c37 --customer "ACME GmbH"
    --expires 2027-12-31

Option	Meaning
--server	The customer’s server ID
--customer	Shown on the Plugins page
--expires	The last day it is valid; without it the license never expires
--features	The features it unlocks, separated by commas (the project property OadmLicenseFeatures takes ;); without it every feature
--limit	Optional: a number your plugin enforces, for example sites=3; repeat for more
--out	The file name (default <customer>-<plugin id>.oadmlicense)

The result is one line, the license key, printed and written to the file:

OADM1.eyJwbHVnaW4iOiJhY21lLnNpdGUtcmVwb3J0cyIsInNlcnZlciI6IjdmM2MyYTFlLTViOGQtNGM2Zi05YTJlLTFkMGI0ZThmNmMzNyIs....MEUCIQ...

Send the customer the key or the file. The key carries the plugin, the server ID, the customer, the dates and, when you gave them, the features and limits, signed with your private key; any change breaks the signature. Spaces and line breaks a mail program adds are ignored. To sign from your own shop instead of oadm license sign, call LicenseFile.Sign of the SDK (Oadm.Sdk.Licensing) with the same data and key.

4. Check the license in the plugin

The license is in every context of your plugin: ICorePluginContext.License, ITaskExecutionContext.License and IActionContext.License. It is live: it changes when the customer enters or removes a license and when it or the trial runs out.

public Task StartAsync(ICorePluginContext ctx, CancellationToken ct)
{
    _license = ctx.License;
    if (_license is not null)
    {
        _license.Changed += (_, _) => ctx.Logger.LogInformation("License: {Reason}", _license.Current.Reason);
    }

    return Task.CompletedTask;
}

public async Task<string?> InvokeAsync(string method, string? payloadJson, CancellationToken ct)
{
    if (_license is { IsValid: false })
    {
        throw new InvalidOperationException(_license.Current.Reason); // "The trial ended on 2026-11-15. Enter a license."
    }

    if (method == "export" && _license?.Has("export") == false)
    {
        throw new InvalidOperationException("Your license does not include the export.");
    }

    var sites = _license?.Limit("sites"); // only when you sell limits; null = no limit
    ...
}

Member	Meaning
IsValid	A valid license, a running trial, or no license needed
Has(feature)	The license lists the feature or lists none; always true during the trial
Limit(name)	The limit of a valid license, null when it sets none or during the trial, 0 without a valid license
Current.Status	Valid, Trial, TrialEnded, Missing, Expired, WrongServer, Invalid, NotRequired
Current.Reason	One plain sentence for your messages, for example “Licensed to ACME GmbH until 2027-12-31.”
Current.Data	Customer, dates, features and limits of a readable license
Changed	Raised when the state changed

OADM only checks. Your plugin decides what runs without a valid license: nothing, a limited version, or a reminder. License is null on hosts without licenses (older OADM): treat that as you prefer.

A plugin page reads the same state with ICorePluginClientContext.LicenseOf(packageId), for example to show “No license” or to lock buttons. The server part must check again, because a client can be changed.

On the Plugins page

While a plugin needs a license, administrators see the server ID with a copy button and a License column: the state (Licensed, Trial, Trial ended, No license, Expired, Other server, Not valid) with the reason as tooltip, Enter license (paste the key or choose its file; below the field OADM shows whom the key is for, and a key that does not fit is refused with the reason; the button reads Change license once a key is stored) and Remove. Entering and removing a license is written to the audit log.