Ability to associate purchases to account

This feels like an odd feature request to make because it’s usually table stakes for anyone selling stuff like this to either make an obvious way to create an account while making a first purchase (and make the disadvantages of not doing so obvious) or make it possible to associate a purchase with your account after the fact. I don’t know how you guys have implemented your database, but I imagine there’s some row representing my purchase that’s assigned to some user id that represents a “guest” user… and all you’d have to do is change that id. Or at most, you’d have to simulate a new transaction. But I’m told it can’t be done at the moment. So yeah… a nice feature would be to be able to have a purchase I made associated with an account (and/or a more streamlined way of creating an account with that first purchase)… which again, I’d expect to already exist.