I hit my weekly usage limit using chatgpt auth.
I have ~2 days until the limit resets so I thought I would try using apikey auth.
I followed the instructions and got errors such as:
■ unexpected status 400 Bad Request: {
"error": {
"message": "The encrypted content gAAA...lA== could not be verified.",
"type": "invalid_request_error",
"param": null,
"code": null
}
I tried several ways to get it to work.
Finally I thought that maybe it was the session itself.
So, instead of resuming a session I just started a fresh session and that worked fine.
Smack! 
I tried resuming my originally “chatgpt” session again and get the same error.
I think the use case of hitting your limit and then switching to pay-per-use would be pretty common.
Sucks that it isn’t supported!
A user just has to kiss their previous [possibly large] session away and start over?
Yikes!
Maybe someone at OpenAI should use Codex to implement a fix for that!