近年因數位化發展，數位商品漸漸取代實體商品成為市場大宗商品，軟體開發商間的競爭愈來越強烈，相似產品的相繼出現，其中兩產品間綜效關係將會影響彼此之收益，因此除了需考慮銷售商品的特點外，新進產品的綜效關係也將成為策略選擇與定價的關鍵。本研究考量兩期價格競爭，成員為既有廠商和新進廠商，兩廠商品在市場競爭且目標皆為利潤最大化。既有廠商於初期決定是否提供升級優惠價格，在第一期對初始產品定價，第二期根據銷售方式對升級產品定價；新進廠商則會在第二期進入市場前決定是否推出訂閱銷售模式，並推出一款新產品。市場上的消費者具策略性思考，會綜觀廠商的長期銷售模式來做為自己選擇的依據。
本研究對兩廠商選擇之不同銷售策略下之四種情境，推導兩廠商利潤極大化之均衡價格，且對其決策變數與利潤進行性質分析與參數敏感度分析，最後探討兩廠商之銷售策略選擇偏好，用以了解不同情況下兩廠商會將如何選擇銷售策略，與說明各情境與參數變化對其獲利績效影響。最後，提供相關管理意涵於供應鏈中管理者。
在本研究利用性質分析與數值分析推導各參數對兩廠商決策變數之趨勢和情境利潤比較分析後，既有廠商在以下條件下適合提供升級優惠：(1)綜效程度高、(2)初始產品效用低、(3)等待折扣高、(4)時間折扣低、(5)既有升級程度高且綜效程度低時；新進廠商則是在以下條件下適合選擇訂閱制：(1)綜效程度較高、(2)新進產品升級程度高、(3)綜效程度低且新進產品升級程度低。

The relationship in software will be a big issue for their selling. Except identify the features of own product, the relationship with competitive product will be the key point of choosing selling strategy and pricing.
This research uses two periods model. The roles in model include an incumbent software developer and an extraneous software developer. They will compete in the market and both hope to achieve the objectives of maximum profits. The incumbent developer should decide whether to provide upgrading discount price or not before selling process. Extraneous developer enters market and decide whether to use subscription policy or perpetual licensing before entering the market.
This research considers strategic consumer and derives the subgame theory to get the equilibrium prices in four situations. Using analytical analyze and numerical analyze to investigate how factors influence their decision. And explore the preference of selling strategies between two software developers. According to the conclusion, incumbent developers are suitable to provide upgrade discounts under the following conditions: (1) high synergy effect, (2) low initial product utility, (3) high waiting discount factor, (4) low time discount factor, and (5) high incumbent upgrading rate and low synergy effect.

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