Currently, data is not automatically purged, as often stores re-activate after deactivation (for a variety of reasons). Per PCI compliance we are required to purge unused data occasionally, but we typically leave data for long enough for people to change their minds.
Out of curiosity, I'd love to know why you're asking. Very few people think about issues like this, so it's helpful for us to know where you're coming from and what you're looking for.
Just a heads up, we got a notice from our merchant account provider that Visa is going to start charging a fee for unsettled authorizations of $0.045. Voiding any authorizations you don't want to capture should avoid this.
Out of curiosity, I'd love to know why you're asking. Very few people think about issues like this, so it's helpful for us to know where you're coming from and what you're looking for.