Sorry to hear that you have this impression. All memo IDs generated by you for the BNB currency remain on your account - which you can double check in the Freewallet app.
The issue with OP's case is with the change in deposit address though, not the memo. Do you mean the change did happen then? I think even if you need to change deposit address, there should be a time frame for users to manage it.
From what we've found, there is no mismatch between the user's deposit address and Freewallet's deposit address.
However, the transaction was sent to a completely different address. We are waiting for clarifications from the user in the support ticket.