<?php
class Custom_class{
	public function __construct(){
		add_action('woocommerce_checkout_order_processed', array($this, 'checkout_processed'), 10, 3);
	}

	public function checkout_processed($order_id, $posted_data, $order){

		// get all coupons in cart
		$cc = $order->get_items('coupon');

		// if no coupons used return
		if( !$cc ) return;

		// run through for each coupons used in cart
		foreach($cc  as $cc1){

			// if coupon code is free $5 coupon
			if($cc1->get_code() == 'giftevo2020'){

				// save to user meta 
				update_user_meta( $this->current_user->ID , 'evo_coupon_used_2020', 'giftevo2020');
			}
		}
	}
}
new Custom_class();

<?php
public function dashboard(){
	// GIFT Cash		
	$hide_gift = true;
		
		// check if current user has coupon code in user meta
		$this->current_user = wp_get_current_user();
		$coupon_used = get_user_meta( $this->current_user->ID, 'evo_coupon_used_2020');
		
		// if this use has not used coupon code show special message
		if(!in_array('giftevo2020', $coupon_used) ):
	?>
		<div class='b50' style='    background: linear-gradient(45deg, #ff5b9d, #ff9570); color: #fff;'>
			<h2>Our Gift to You</h2>
			<p style='line-height: 1.3;font-size: 36px;'>$5 Free Cash to Spend</p> 
			<p>Code at checkout: <b>GIFTEVO2020</b></p>
			<p>Use this free cash to purchase any of our addons before Dec. 2nd, 2020</p>
			<p><a class='btn btn_grey' href='https://www.myeventon.com/addons/'>Find Addons</a></p>
		</div>

	<?php endif;  
}

<?php
class Custom_class{
	public function __construct(){
		add_action('woocommerce_checkout_order_processed', array($this, 'checkout_processed'), 10, 3);
		add_action('woocommerce_account_dashboard',array($this,'dashboard') );
	}

	public function checkout_processed($order_id, $posted_data, $order){

		// get all coupons in cart
		$cc = $order->get_items('coupon');

		// if no coupons used return
		if( !$cc ) return;

		// run through for each coupons used in cart
		foreach($cc  as $cc1){

			// if coupon code is free $5 coupon
			if($cc1->get_code() == 'giftevo2020'){

				// save to user meta 
				update_user_meta( $this->current_user->ID , 'evo_coupon_used_2020', 'giftevo2020');
			}
		}		
	}
	public function dashboard(){		

		// GIFT Cash		
		$hide_gift = true;
			
			// check if current user has coupon code in user meta
			$this->current_user = wp_get_current_user();
			$coupon_used = get_user_meta( $this->current_user->ID, 'evo_coupon_used_2020');
			
			// if this use has not used coupon code show special message
			if(!in_array('giftevo2020', $coupon_used) ):
		?>
			<div class='b50' style='    background: linear-gradient(45deg, #ff5b9d, #ff9570); color: #fff;'>
				<h2>Our Gift to You</h2>
				<p style='line-height: 1.3;font-size: 36px;'>$5 Free Cash to Spend</p> 
				<p>Code at checkout: <b>GIFTEVO2020</b></p>
				<p>Use this free cash to purchase any of our addons before Dec. 2nd, 2020</p>
				<p><a class='btn btn_grey' href='https://www.myeventon.com/addons/'>Find Addons</a></p>
			</div>

		<?php endif;  
	}
}
new Custom_class();