I have an ordinary website (no WooCommerce function), and now adding woocommerce plugin to enable it with selling functions.

Now I have some existing customer members from the real-world shop, how to add these real-world members to this “new online shop with woocommerce plugin”? so that these old member can enjoy some privileges in this online shop.

Do I need to buy one more "WooCommerce Subscriptions Plugin" to incorporate it?