The word '会々員' is an old word, and in today's Japanese, '会員' is used.
Sorry, I was explaining it wrong.
"会々員" is not an old word, it's still in use today.
Here is the explanation of the "セイコー会々員の店" again.
The kanji "々" is a substitute character that can be used when the same kanji as the previous one is used consecutively.
In other words, "セイコー会々員の店" can be rewritten as "セイコー会会員の店".
Furthermore, if you rewrite "セイコー会会員の店" in a form that is easily translated by a translation service, it becomes "セイコー会 会員の店".
"セイコー会" is the name of the organization( or society? or group?).
I don't know if "セイコー会" is an official organization of Seiko or not. I'm sorry...
In other words, the meaning of "セイコー会々員の店" is "Seiko-kai" Member's Store.
I tried to look up "増田時計店", but I couldn't find where it was.
The signboard looks retro.
😀