A Byond membership lasts 365 days which is AWESOME but it also means that I can't change my account name to suit what I'm currently running with. Well.. I could create another account and buy it a membership but I don't have the money to do that just for a name change.

Perhaps if we could pay something like 2 dollars when we wanted to change our names, I'd do it. What about you guys?
It is unlikely that name changes will ever be allowed, just because of the mess it would make (particularly with hard-coded key names in games). This is the same reason old keys aren't deleted.

However, the staff have (on occasion) been willing to transfer a relatively new membership to a different key. You could try asking them through the support form, but they aren't obligated to do so.