Extending the Filament Middleware to verify if a tenant is billable. Read more and learn an even better way: https://silvanhagen.com/free-users-filament-laravel-spark/

VerifyProjectIsBillable.php

<?php

namespace App\Http\Middleware;

use Filament\Billing\Providers\Http\Middleware\VerifySparkBillableIsSubscribed;
use Filament\Facades\Filament;

class VerifyProjectIsBillable extends VerifySparkBillableIsSubscribed
{
    public function handle($request, $next, $subscription = 'default', $plan = null)
    {
        $project = Filament::getTenant();

        if ($this->shouldRedirectToBilling($project, $request)) {
            return parent::handle($request, $next, $subscription, $plan);
        }

        return $next($request);
    }

    protected function shouldRedirectToBilling($project, $request): bool
    {
        return $project
            && $project->isBillable()
            && ! $project->isOnTrialOrSubscribed();
            && $request->route()->named([
                'filament.admin.resources.feedback.index',
                'filament.admin.resources.feedback.create',
                'filament.admin.resources.feedback.edit',
                'filament.admin.resources.feedback.show',
            ]);
    }
}