The serial number entered can't be used to activate AccountRight Standard 2025.11 files

I upgraded my offline file recently and then chose to open upgraded file, receiving the message 'Error 'You have reached the transaction limit of your company file'

I submitted a support request and received an email with the MYOB AccountRight licence file attached. After proceeding to activate the file I then received the message 'Unable to activate 2025.11 files' ' The serial number entered can't be used to activate AccountRight Standard 2025.11 files.'

Submitting another support request, it was suggested I download the latest version from 

and install. Then the file will be able to be opened.'

Unfortunately, I received the message regarding the serial number again. I have tried to uninstall and then reinstall myob without luck. I keep getting the message above.

I have tried to restore a back up, the serial number message appears.

This offline file has been operating for years, and I do have an online and another offline file which has had no problems upgrading. My contact with MYOB support began on Monday 19th January, so far without success. 

I have not added new files so I am really confused as to what has happened. 

As I can not log into the file I can only assume the build is 2025.11.1.9

I have spent many many hours reading through the Community Forum and I simply do not know how to fix the issue. Can anyone please offer a suggestion. Thank you so much.