MemberPress: Return to Same Page After Signup

function mepr_cust_registration_input( $product_id ) {

  $post_id = url_to_postid( wp_get_referer() );

  if( isset( $post_id ) && $post_id ) {

  	$input_str = "<input type='hidden' name='mepr_cust_current_page_id' id='mepr_cust_current_page_id' value='{$post_id}'/>";

  	echo $input_str;

  }

}

add_action( 'mepr-checkout-before-submit', 'mepr_cust_registration_input' );

function mepr_cust_thankyou_url_params( $url, $args ) {

  if ( isset( $_REQUEST[ 'mepr_cust_current_page_id' ] ) && $_REQUEST[ 'mepr_cust_current_page_id' ] ) {

    $param_str = http_build_query( $args );

    $url = get_permalink( $_REQUEST[ 'mepr_cust_current_page_id' ] );

    if( strpos( $url, '?' ) ) {

      $url .= '&';

    } else {

      $url .= '?';

    }

    $url .= $param_str;

  }

  return $url;

}

add_filter( 'mepr-thankyou-page-url', 'mepr_cust_thankyou_url_params', 10, 2 );