You can show such product labels using an app like the followings. You can configure the labels as you need: Product Labels & Badges Pro
You may also like to try this app to boost your Cart conversion rate by showing selected coupon codes on your cart page: Voila: Power Coupons on Cart
Will love to know if this helps.
You can consider using ModeMagic Product Badge app to apply custom badges, sticker to your product images.
PageFly page builder also have the option to show badge auto-apply the discount code of your products
Hope you find this helpful.