How to redirect the user to a product page (node) after payment is made? How to redirect the user to a product page (node) after payment is made?

I'm using the Commerce Express Checkout module. That's why in the Shopping cart can be just one product.
One option is to use hook_menu_alter in a custom module to override your current destination page with a redirect. 

&lt;?php

function mymodule_menu_alter(&amp;$items) { 

    $items['current/checkout/path'] = array(
        'page callback' =&gt; 'drupal_goto',
        'page arguments' =&gt; array('new/checkout/path'),
        'access callback' =&gt; TRUE,
      );

}


Update:

To use the above code, you'll have to create a module.

1) Create a directory to be used for this module, e.g. /sites/all/modules/MYMODULE

2) Create MYMODULE.info, e.g. /sites/all/modules/MYMODULE/MYMODULE.info. Paste the following into the file.

name = MYMODULE
description = "Module description."
package = Custom
core = 7.x


3) Create MYMODULE.module, e.g. /sites/all/modules/MYMODULE/MYMODULE.module. Paste the following into the file.

&lt;?php

function MYMODULE_menu_alter(&amp;$items) { 

    $items['current/checkout/path'] = array(
        'page callback' =&gt; 'drupal_goto',
        'page arguments' =&gt; array('node/123'),
        'access callback' =&gt; TRUE,
      );

}


4) Replace all instances of MYMODULE with your desired module name. Replace current/checkout/path with the current path of the checkout. Replace node/123 with the new checkout path. Lastly, enable your new module.

This will tell Drupal to replace the current checkout page with a redirection to the new one.