Abandoned checkout still registers users


When a user decides to register for a subscription on my site they are first taken to the page asking them to fill out their profile details. Following this, they are taken to the page to choose which subscription they want to register for. However, if the user abandons the checkout process here, the user remains registered to the site (just not asigned a subscription).

Is it possible not to register the user at all if the user abandons the checkout process for a paid membership? Having inactive users in the database makes management much more complex. Also, if the person comes back and decides he/she wants to pay for a membership using the same username or email as before, he/she can't since it will already be taken (as an inactive account).

Many thanks