"I've bought a new serial number but I'm still getting a message that my account expires soon."
When you renew or buy Bet Angel for the first time you will need to register a serial number to activate your license. When you do this your account will be extended by the amount of time purchased.
For example, if you purchase a two month subscription but still have a little time left on your trial or existing subscription then, by registering your serial number, the next term gets added to your existing subscription.
Register your serial number by following the instructions here: -