If you haven't already changed to the class licence, then when your current licence expires you automatically get transferred to the class licence, and then five years after that, you get asked it you wish to retain the licence.
If you choose to transfer before the current licence expires, then you get a pro-rata refund.
From the WIA Website:-
From 19th February 2024 the ACMA issues amateur callsigns. More information can be found on the ACMA website.
Link
Callsigns are issued on an ongoing basis. Every five years the ACMA will contact callsign holder via a person's preferred method on contact with the ACMA; email or postal address, seeking confirmation of on-going use. It is important to keep your contact details up to date, as when the ACMA contacts you in regard to your callsign(s) and receives no response after a period of time, they may deem these available for re-allocation.
But the question remains, how do you prove your licence is current to a third party like the DMR radio id
I guess you ask the ACMA for the details? Which you can do using the ACMA assist website.
You have to create an account but you will get the licence expiry details.
go to
https://www.acma.gov.au/acma-assist create an account, and select licence details. Mine looks like this.