Best Practices

Implementation Strategy

Key Principle: Fail Gracefully

Always design your kill-switch to fail in a way that maintains customer trust.

1. Choose the Right Failure Mode

Fail-Open (Recommended)

Allow access when checks fail. Best for maintaining customer relationships.

Show upgrade prompts
Limit premium features
Continue basic functionality

Fail-Closed (Strict)

Block access when checks fail. Use only for high-security scenarios.

Complete application shutdown
Hard license enforcement
High-security requirements

2. Cache Strategically

CacheTtlMinutes: 60 (Recommended)

Low TTL (1-15 minutes): High security, frequent checks
Medium TTL (30-60 minutes): Balanced approach
High TTL (2-24 hours): Better performance, less security

Security Best Practices

1. API Key Management

Never commit API keys to version control

Use environment variables
Implement key rotation (every 90 days)
Use different keys for different environments
Monitor key usage in dashboard

2. Code Obfuscation

Make reverse engineering difficult:

// Good: Innocent-looking code

var analytics = AnalyticsClient.Initialize();

await analytics.ValidateLicenseAsync();

// Avoid: Obvious kill-switch code

var killSwitch = KillSwitchClient.Create();

if (!await killSwitch.CheckAsync()) Exit();

Integration Patterns

1. Application Startup

// .NET Console Application

public static async Task Main(string[] args)

{

var licenseCheck = await LicenseValidator.ValidateAsync();

if (!licenseCheck.IsValid)

return ShowTrialExpiredMessage();

await RunApplicationAsync();

}

2. Periodic Checks

// Background service for long-running apps

public class LicenseMonitor : BackgroundService

{

protected override async Task ExecuteAsync(CancellationToken stoppingToken)

{

while (!stoppingToken.IsCancellationRequested)

await ValidateLicensePeriodically();

await Task.Delay(TimeSpan.FromHours(1), stoppingToken);

}

Customer Experience

1. Graceful Degradation

✅ Good Experience

"Your trial has ended. Upgrade to continue."
Show upgrade options
Allow basic functionality
Provide support contact

❌ Poor Experience

"Access denied. Contact administrator."
Immediate application exit
No explanation or help
Technical error messages

2. Communication Strategy

Before expiration: Send renewal reminders
At expiration: Show clear upgrade paths
After expiration: Provide grace periods when possible
Support: Make it easy to contact support

Monitoring and Analytics

1. Dashboard Monitoring

Monitor daily check counts
Track blocked attempts
Set up alert thresholds
Review customer activity

2. Logging Strategy

// Log license check events

logger.LogInformation("License check for {CustomerId}: {Status}",

customerId, result.Allowed ? "Allowed" : "Blocked");

3. Performance Considerations

Scenario	Recommended TTL	Network Calls
Desktop Application	2-4 hours	~6-12 per day
Web Application	15-30 minutes	~48-96 per day
Mobile Application	1-2 hours	~12-24 per day