Here are a few options for a WordPress post_tag description, catering to different levels of formality and clarity. Choose the one that best suits your needs:

**Option 1 (Concise and Clear):**

* **Description:** 標註文章中與產品、服務或優惠的有效期限相關的內容。 (Marks content related to the expiration dates of products, services, or promotions within the article.)

**Option 2 (More Descriptive):**

* **Description:** 用於標記文章中關於有效期限的內容。這包括產品的保質期、促銷活動的截止日期、合約的到期日等。 (Used to tag content concerning validity periods within the article. This includes shelf life of products, deadlines for promotional activities, expiration dates for contracts, and so on.)

**Option 3 (Focus on Relevance):**

* **Description:** 標記涉及時效性的文章，讓讀者快速找到與有效期限、到期日相關的信息。 (Tags articles related to timeliness, allowing readers to quickly find information concerning expiration dates, deadlines, and validity periods.)

**Option 4 (For a Tech or Product-Focused Blog):**

* **Description:** 標記與產品、軟體、訂閱或支援的有效期限相關的文章。 (Tags articles related to expiry of products, software, subscriptions or the support provided.)

**Key Considerations When Choosing:**

* **Audience:** Who are you writing for? A general audience needs simpler descriptions.
* **Content Focus:** What kind of content are you primarily tagging? Tailor the description to fit.
* **SEO:** While descriptions are less influential than the tag/keyword itself, think about what keywords potential readers might use to search for your content.

I recommend using the first one (Option 1) or the third one(Option 3) as they are simple, accurate, and easily understood. The description should ideally be clear and concise to help users understand what articles fall under this tag.