Everlusting Life review
Everlusting Life opens at the publisher’s web play address. Pochemu’s terms describe accounts, optional credits and what changes when a player uses a third-party platform.
Pick the platform before buying credits
The terms identify browser versions and authorized third-party platforms. They say third-party platforms can have different payment procedures. Credits can be earned through some in-game or promotional activities or bought, and the terms restrict them to eligible content within the game.

What you are working towards
BoobyLegends gives you a collection to build over a season and publishes what happens to cards when it ends. Everlusting Life’s terms explain which in-game unlocks you can spend credits on. If you plan to switch platforms, check whether the specific purchase carries across before paying.
Anabel’s take
I'd choose where I want to play first, then see which unlocks I actually care about. I'd leave purchases until I had a reason to stick with that account and platform.