Add license limit UI for variable prices and show license key limit in [purchase_history] shortcode.

licence-limit.php

<?php

/**
 * Show license key limit in [purchase_history] shortcode.
 *
 * @since 0.1.0
 */
function edd_site_count_downloads_license_limit_th() {

  echo '<th class="edd-site-count-site-count">' . __( 'Site Count', 'edd-site-count' ) . '</th>';
	
}
add_action( 'edd_purchase_history_header_after', 'edd_site_count_downloads_license_limit_th', 11 );

/**
 * Show license key limit in [purchase_history] shortcode.
 *
 * @since 0.1.0
 */
function edd_site_count_downloads_license_limit_td( $payment_id, $purchase_data ) {
	
	/* Get license limit. */
	$license_limit = edd_site_count_get_license_limit( $payment_id, $purchase_data );
	
	/* translators: If license limit is infinite (0), set it as infinite sign. */
	if ( 0 == $license_limit )
		$license_limit = __( '&#8734;', 'edd-site-count' );
	
	/* Get site count. How many sites have been activated with this key. */
	$site_count = edd_site_count_get_license_count( $payment_id, $purchase_data );
	
	/* If there is no site count, set it to 0. */
	if ( empty( $site_count ) )
		$site_count = 0;
	
	/* Echo site count and license limit to [purchase_history] shortcode. */
	echo '<td class="edd-site-count-site-count">'. $site_count . '/' . $license_limit .'</td>';
	
}
add_action( 'edd_purchase_history_row_end', 'edd_site_count_downloads_license_limit_td', 11, 2 );

/**
 * Get site count.
 *
 * @since 0.1.0
 */
function edd_site_count_get_license_count( $payment_id, $purchase_data) {

	$licensing = edd_software_licensing();
	$downloads = edd_get_payment_meta_downloads( $payment_id );
	
	/* Get license. */
	foreach( $downloads as $download ) {
	$license = $licensing->get_license_by_purchase( $payment_id, $download['id'] );
		if( $license ) {
			return absint( get_post_meta( $license->ID, '_edd_sl_site_count', true ) );
		}
	}

}

/**
 * Get license limit. This is based on price id in variable pricing. This is 0, 1, 2 etc.
 *
 * @since 0.1.0
 */
function edd_site_count_get_license_limit( $payment_id, $purchase_data ) {	
	
	$licensing = edd_software_licensing();
	$downloads = edd_get_payment_meta_downloads( $payment_id );
	
	/* Get license. */
	foreach( $downloads as $download ) {
	$license = $licensing->get_license_by_purchase( $payment_id, $download['id'] );
		if( $license ) {
			
			/* Get license limit. */
			if ( edd_has_variable_prices( $download['id'] ) ) {
			
				/* Get purchase details. */
				$meta = edd_get_payment_meta( $payment_id );
				$cart = edd_get_payment_meta_cart_details( $payment_id, true );
	
				$price_id = false;
	
				/* Get price id from variable pricing. This is 0, 1, 2. */
				foreach( $cart as $key => $item ) {
				
					$price_id = edd_get_cart_item_price_id( $item );
				
					/* Get license limits. */ 
					if( $price_id !== false && ! empty( $price_id ) ) {

						$prices = edd_get_variable_prices( $download['id'] );
						$license_limit_value = '';
						if( $prices && is_array( $prices ) ) {
							$license_limit_value = $prices[ $price_id ]['license_limit'];
						}
				
					}
				}
					
				/* Return license limit. */
				return absint( $license_limit_value );
				
			}	
			else {
			
				return absint( get_post_meta( $download['id'], '_edd_sl_limit', true ) );
			
			}
		}
	}
}

/**
 * Adds the table header for license limit.
 *
 * @since 0.1.0
 */
function edd_site_count_license_limit_variable( $post_id ) { ?>

	<th style="width: 90px"><?php _e( 'License limit', 'edd-site-count' ); ?></th>
	
	<?php

}
add_filter( 'edd_download_price_table_head', 'edd_site_count_license_limit_variable' );

/**
 * Adds the table cell for license limit.
 *
 * @since 0.1.0
 */
function edd_site_count_row_license_limit( $post_id, $key, $args ) {

	$license_limit = isset( $args['license_limit'] ) ? $args['license_limit'] : null;
	
	?>

	<td>
		<input type="text" class="edd_site_count_license_limit" value="<?php echo esc_attr( $license_limit ); ?>" placeholder="<?php _e( 'License limit', 'edd-site-count' ); ?>" name="edd_variable_prices[<?php echo $key; ?>][license_limit]" id="edd_variable_prices[<?php echo $key; ?>][license_limit]" size="20" style="width:90px" />
	</td>
	
	<?php

}
add_action( 'edd_download_price_table_row', 'edd_site_count_row_license_limit', 10, 3 );

/**
 * Adds license limit to edd_price_row_args.
 *
 * @since 0.1.0
 */
function edd_site_count_row_args_license_limit( $args, $value ) {

	$args['license_limit'] = isset( $value['license_limit'] ) ? $value['license_limit'] : '';

	return $args;

}
add_filter( 'edd_price_row_args', 'edd_site_count_row_args_license_limit', 10, 2 );

?>

get_license_limit function in Software Licensing needs to check variable prices limit also. Fallback could always be _edd_sl_limit.