Here are a few options for a description of the WordPress post_tag “單筆購買” (Single Purchase) in Traditional Chinese, ranging in formality and specificity, along with their potential uses:

**Option 1: Simple and Direct**

* **Description:** 透過單筆交易購買的商品或服務。 (Goods or services purchased via a single transaction.)
* **Use:** Suitable for most general contexts, clear and concise. Good for a broad understanding of the tag’s purpose.

**Option 2: More Contextual & Usable in an Online Shop or eCommerce Website**

* **Description:** 此標籤用於標記以單次購買方式提供的商品或服務，與訂閱或定期付款方式區別。 (This tag is used to mark products or services offered through single-purchase transactions, as opposed to subscriptions or recurring payments.)
* **Use:** Excellent for e-commerce sites. Highlights a contrast with subscription models.

**Option 3: Focusing on the Action**

* **Description:** 針對想要一次性購買，不必承擔續訂或多次付款責任的客戶所提供的產品。 (Products offered for customers who want to make a one-time purchase and do not wish to commit to renewal or multiple payments.)
* **Use:** Great for highlighting the advantage of single purchases for customers.

**Option 4: Emphasizing the Simplicity**

* **Description:** 簡單、方便的單筆購買選項。 (Simple and convenient single-purchase options.)
* **Use:** Focuses on the user experience, highlighting ease of use.

**Option 5: More Formal, good for legal/technical website**

* **Description:** 標示以單筆交易完成的購買行為，買方在單次付款後，取得商品或服務的使用權利。(Denotes purchase transactions completed via a single payment, where the buyer acquires the right to use a product or service after a one-time payment.)
* **Use:** Great choice for product or service that might have legal notes (e.g. digital products)

**Key Considerations When Choosing:**

* **Your Website’s Niche:** Tailor the description to the specific products/services you offer.
* **Target Audience:** Consider their level of technical understanding.
* **SEO:** While tag descriptions aren’t as heavily used as titles or content, you can include relevant keywords.

**How to Use in WordPress:**

1. **Go to your WordPress Admin Dashboard.**
2. **Navigate to Posts > Tags (or Products > Tags, if you’re using WooCommerce).**
3. **Find the tag “**單筆購買**” (Single Purchase / If the tag doesn’t exist yet, create it first).**
4. **Click the “Edit” link below the tag title.**
5. **In the “Description” field, paste the description you selected above.**
6. **Click “Update”.**

By using a descriptive tag description, you help users and search engines understand the context of your content, improving organization and SEO. Good luck!