common config main.php

<?php
return [
    'aliases' => [
        '@bower' => '@vendor/bower-asset',
        '@npm' => '@vendor/npm-asset',
    ],
    'vendorPath' => dirname(dirname(__DIR__)) . '/vendor',
    'components' => [
        'cache' => [
            'class' => 'yii\caching\FileCache',
        ],
        'balanceManager' => [
            'class' => 'yii2tech\balance\ManagerDb',
            'accountTable' => '{{%BalanceAccount}}',
            'transactionTable' => '{{%BalanceTransaction}}',
            'accountLinkAttribute' => 'accountId',
            'amountAttribute' => 'amount',
            'dataAttribute' => 'data',
        ],
    ],
];

frontend controllers SiteController.php

<?php

namespace frontend\controllers;

use Yii;
use yii\base\InvalidParamException;
use yii\helpers\VarDumper;
use yii\web\BadRequestHttpException;
use yii\web\Controller;
use yii\filters\VerbFilter;
use yii\filters\AccessControl;
use common\models\LoginForm;
use frontend\models\PasswordResetRequestForm;
use frontend\models\ResetPasswordForm;
use frontend\models\SignupForm;
use frontend\models\ContactForm;

/**
 * Site controller
 */
class SiteController extends Controller
{
    /**
     * Displays homepage.
     *
     * @return mixed
     */
    public function actionIndex()
    {
        /** @var \yii2tech\balance\ManagerDb $balanceManager */
        $balanceManager = Yii::$app->balanceManager;

        $user1 = 1;
        $user2 = 2;

        // add 500 credits to $user1
        $balanceManager->increase($user1, 500);
        // remove 100 credits from $user1
        $balanceManager->decrease($user1, 100);

        // remove 100 credits from $user1 and add 100 credits to $user2
        $balanceManager->transfer($user1, $user2, 100);


        VarDumper::dump([
            'user1balance' => $balanceManager->calculateBalance($user1),
            'user2balance' => $balanceManager->calculateBalance($user2),
        ], 10, true);
        die;
    }

    /// ...
}

m171216_150421_create_balance_tables.php

<?php

use yii\db\Migration;

/**
 * Class m171216_150421_create_balance_tables
 */
class m171216_150421_create_balance_tables extends Migration
{
    /**
     * @inheritdoc
     */
    public function safeUp()
    {
        $this->createTable('BalanceAccount', [
            'id' => $this->primaryKey(),
            'balance' => $this->integer()->notNull()->defaultValue(0),
            // ...
        ]);

        $this->createTable('BalanceTransaction', [
            'id' => $this->primaryKey(),
            'date' => $this->integer()->notNull(),
            'accountId' => $this->integer()->notNull(),
            'extraAccountId' => $this->integer()->notNull()->defaultValue(0),
            'amount' => $this->integer()->notNull()->defaultValue(0),
            'data' => $this->text(),
            // ...
        ]);
    }

    /**
     * @inheritdoc
     */
    public function safeDown()
    {
        $this->dropTable('BalanceTransaction');
        $this->dropTable('BalanceAccount');
    }
}