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会員 as a pure noun, 現実 as a noun that means a state, 健康 as a state (adjective), 表示 as a state as well as action, and 使用 as a pure action.

会員 as an identity (to be a thing), 現実 as a thing as well as state, 健康 as a state (adjective), 表示 as a state as well as action, and 使用 as a pure action.

Despite the question seems to have reached its own solution, I'd like to make a new answer, for I find the existing explanations do not lead to correct understanding of the topic.

All these words have their own meanings usually not directly translated to English affixes like "non-", "in-", "un-", "-less" etc., so I'm going to explain them descriptively. What they have in common is negative meaning and ability to attach to 漢語 (Sino-Japanese) words.
(I didn't consider much about two-character compounds like 不安, 非道, 無常, 未婚 etc. because these words are better memorized en bloc.)

Despite the question seems to have reached its own solution, I'd like to make a new answer, for I find the existing explanations would not lead to a correct understanding on this topic.

Each of these words has their own meaning, which usually cannot be directly translated to English affixes like "non-", "in-", "un-", or "-less", so I'm going to explain these terms descriptively. 

What they have in common is negative meaning and ability to attach to 漢語 (Sino-Japanese) words.
(I didn't consider much about two-character compounds like 不安, 非道, 無常, 未婚 etc. because these words are better memorized en bloc.)

Quick chart

会員 as a pure noun, 現実 as a noun that means a state, 健康 as a state (adjective), 表示 as a state as well as action, and 使用 as a pure action.

　　　　不　　　　非　　　　無　　　　未
会員　　×　　　　○　　　　○　　　　×
現実　　×　　　　○　　　　△　　　　？
健康　　○　　　　○　　　　×　　　　？
表示　　○　　　　○　　　　○　　　　○
使用　　○　　　　△　　　　○　　　　○