public function applies_to_plan( $plan_id ) {

		if ( $plan_id instanceof LLMS_Access_Plan ) {
			$plan = $plan_id;
		} else {
			$plan = new LLMS_Access_Plan( $plan_id );
		}

		// Check if it can be applied to the plan's product first.
		if ( ! $this->applies_to_product( $plan->get( 'product_id' ) ) ) {
			return false;
		}

		// If the coupon can only be used with one-time plans and the plan is recurring.
		if ( 'one-time' === $this->get( 'plan_type' ) && $plan->is_recurring() ) {
			return false;
		}

		return true;
	}