One account, one wallet. What you earn in the Zulu campaign is spendable in the fresco workshop, because the balances belong to you rather than to a game.
The three platform balances
ELK Coin is the everyday currency. It is what sessions, daily rewards and achievements pay out in, and what most things cost. You will never be asked to buy it to keep playing.
ELK Gem is the premium currency. It exists so that a purchase has somewhere to land; nothing that affects whether a puzzle can be solved is behind it.
ELK Experience is not spendable at all. It only ever goes up, and it is the record of how much you have actually played across every game rather than in one.
Currencies that belong to a game
A game may declare its own currency alongside those three — Africa Puzzle Empire has one, its gold. A game currency is spent inside that game and is deliberately not convertible: it exists so a game can tune its own economy without touching the platform's, and so that the balance in your wallet keeps meaning what it says.
Your wallet shows both kinds, side by side, on your account page.
Every movement is a line in a ledger
A balance here is not a number stored somewhere and edited. It is the sum of a ledger, and every entry records what happened: which game, which reward or purchase caused it, the amount, the balance before and the balance after, and when. The last entries are on your account page; the full history is kept.
That design has one consequence worth stating plainly. Nothing your device sends can change a balance. A phone can ask to start a session and report the moves that were played; the amount paid for them is worked out on our servers from those moves. There is no message a client can send that means "add a thousand coins", because there is no code on our side that would accept one.
It costs a round trip. What it buys is that a balance means something — and that a leaderboard and an economy cannot be quietly emptied by whoever is most willing to modify an app.
What if a balance looks wrong
Open your account page and read the last entries. Nearly every surprise has a line explaining it: a daily reward that arrived, a purchase, a session that was replayed and refused.
If a line is missing or one is there that you cannot account for, tell support with the date and roughly what you were doing. Every entry has an identifier and a reason recorded against it, so this is a question that can actually be answered rather than guessed at.