Developer API

long tokens = FlareTokensAPI.getTokens(player);           // online player
FlareTokensAPI.giveTokens(player, 100);
if (FlareTokensAPI.takeTokens(player, 50)) { /* bought */ }
FlareTokensAPI.fetchTokens(uuid).thenAccept(t -> { });     // anyone, also offline

TokensChangeEvent is called before the balance of an online player changes and can be cancelled. Add softdepend: [FlareTokens] to your plugin.yml.