Your API key, once
Stored against the account so every device reads the same trading post, wallet and character data.
Capital limits
Working capital and the amount you hold back travel with you — the capital ceiling on the table respects both.
Realized ledger
Every filled sale is kept with its cost basis, so profit, win rate and average hold survive a reload.
Watchlist and positions
Open orders you flagged stay flagged, and undercut warnings arrive against your own listings.