expression
not getting tired; never boring
Jocular expression based on the reading あきない (from 飽きない, 'not get tired of'). The kanji 春夏冬 omit 秋 (autumn), creating a visual pun.
このゲームは春夏冬だね。
This game never gets old, huh.
expression
Jocular use of the same kanji to represent 商い (business), often seen in shop names or signs. The reading あきなし is an older variant.
あの店の看板には「春夏冬」と書いてある。
That shop's sign says '春夏冬' (a playful way to write 'business').
Ateji wordplay: the kanji 春夏冬 (spring, summer, winter) omit 秋 (autumn), yielding the reading あきない, which can mean either 飽きない (not getting tired) or 商い (business).