API creadit not accumulation over separate billing

Hello i was using photoroom api basic plan with $200 last month for 10k img processing (rembg task), my credits is nearly runout - used 80%.
So yesterday i purcharse another 10k with $200, i realize my remaining credits also reset to 10k, which expected to be 10k + 2k remain.
Maybe i have mis-understanding something, or should i make a refund, im planning to use photoroom in long term, with a flexible billing plan instead of prepaid and have accumulation creadit for more reasonable and economical.
Also i am using this email for all purchase and api call, if that provide more info.

Very much appreciate!

Hi there,

Thanks for flagging this with us. Based on what I am seeing in our backend, it looks like your initial purchase date was Aug 12th (200), and you renewed this Sept 15, which means that your credits from August would expire on the 12th as these do not roll over month over month.

Let me know if those dates don’t align with what you’re seeing on your end? Hope this helps provide clarity!

Best,