After installing the Dokan plugin you should get a menu like this in your wp-admin. But sometimes. Due to plugin conflict the menu item can get hidden.
WordPress has function to add menu items for themes and plugins in wp-admin and those custom added menu items has ordering to determine where it will appear. To know more about this function, you can read this doc http://codex.wordpress.org/Function_Reference/add_menu_page
In Dokan plugin, we have used this function in
includes/admin/admin.php line number 67 and the menu position is located at line 58. On that line, you will see something like this
$menu_position = apply_filters( 'doakn_menu_position', 17 );
Here 17 is the menu order. If another plugin or theme tries to use this very same position, then you can change it from here.
After changing the menu order to 7 instead of 17, Dokan menu will move up like this
The best practice is overriding anything from your child theme. If you do so, then you will not have to edit the plugin file each time when it gets updated.