The Enterprise Client Administration is shipped with a few useful CLI commands. To execute them you need shell access to the Enterprise Client Administration server, go to the install directory and execute
app/console to get a list of all available commands.
cd _ECA_ app/console
Synchronize all licenses from your account to all registered shops.
app/console sbp-account:create --shopwareId="_SHOPWAREID_" --password="_PASSWORD_"
Link a account with the ECA, requires a password and the Shopware ID.