How long do the physiological effects of 6 months of depression/anxiety last? my memory isn't as good as it was, and it's difficult being creative.

Not too long: Once depression is resolved most of predepression status will return to base line.

Sometimes longer: It depends how many episodes of depression you've had. Depression fundamentally alters brain structure. The more bouts of depression one has, the more likely they are to develop dementia and at a younger age. I'm not saying you are developing dementia, but I am saying that it is plausible that depression can have lasting effects on memory even after you are in remission.