The icon for Membux is coin with a label of a stylized infinity sign with two vertical strokes through it, making it appear as a currency symbol.
Gameplay
Membux are the main currency Agent 8 can obtain and use while traversing the Spire of Order, with more difficult floors yielding a higher amount of Membux when cleared. While their most prominent usage is to purchase various goods at the Vending-Machine Corner floors, they can also be used to escape an uncleared floor, gain another chance when all lives are exhausted, or reroll the available floors or items available in the vending machine as long as the respective hack is active. At the end of every run, Membux are converted to points with a 1:1 ratio, which are then converted to Prlz at a rate of 1:100 (rounded up). If the player progresses past 5F, they will start with 500 Membucks on their next run.
Etymology
Mem likely comes from "memory", with bux coming from "bucks", a colloquial term for money. The English name and names in other languages suggest an association with mem cakes from Splatoon 2: Octo Expansion
Names in other languages
Language
Name
Meaning
Japanese
ネリコイン nerikoin
neri ("dough") + coin
Dutch
Neuri
From neur(o)- (prefix relating to nerves, nervous tissue or the nervous system), and euri (hypercorrect and humorous term for "euros")
French (NOE)
Poulpèzes
poulpe ("octopus") + pèze (colloquial term for "money")
German
Memoneten
Memo + Moneten (colloquial term for "money")
Italian
Norilir
From Nori ("Marina") + lire (currency of use in Italy before the euro)
Russian
Вспомбаксы Vspombaksy
Rememberbux
Spanish
Pastimonedas
"Dough-coins". Pasta + Monedas
Chinese (Simplified)
忆界硬币 Yì jiè yìngbì
From 忆界宇宙 (the Chinese name of "Memverse") and 硬币 ("Coin")