You can find documentation in here https://payeer.com/ru/

You can like this listen Plugin events and expand functionality

<?php
use RainLab\User\Models\User as UserModel;
use Shohabbos\Payeer\Models\Transaction;
use Shohabbos\Portal\Models\Payment;

Event::listen('shohabbos.payeer.existsAccount', function ($id, &$result) {
	// find order or account
	$result = UserModel::find($id);
});


Event::listen('shohabbos.payeer.checkAmount', function ($amount, $currency, &$result) {
	// check amount
});

Event::listen('shohabbos.payeer.saveTransaction', function ($postData) {
	// save transaction
    	$transaction = new Transaction();
	$transaction->m_operation_id = $_POST['m_operation_id'];
	$transaction->m_operation_ps = $_POST['m_operation_ps'];
	$transaction->m_operation_date = $_POST['m_operation_date'];
	$transaction->m_operation_pay_date = $_POST['m_operation_pay_date'];
	$transaction->m_shop = $_POST['m_shop'];
	$transaction->m_orderid = $_POST['m_orderid'];
	$transaction->m_amount = $_POST['m_amount'];
	$transaction->m_curr = $_POST['m_curr'];
	$transaction->m_desc = $_POST['m_desc'];
	$transaction->m_status = $_POST['m_status'];
	$transaction->save();
});

Event::listen('shohabbos.payeer.successPayment', function ($id, $amount, $currency) {
    	// add balance or check order as paid
	$user = UserModel::find($id);
	$user->balance += $amount;
	$user->save();

	// add to history payments
	$payment = new Payment();
	$payment->user_id = $id;
	$payment->is_buy = true;
	$payment->amount = $amount;
	$payment->payment_system = 'payeer';
	$payment->date = date('Y-m-d H:i:s');
	$payment->save();
});