Unable to upgrade

I am not able to update active presenter.
My purchase details:
Ref. #: 111898528
License Type: Perpetual
License Volume: 1
Free upgrade is till 2021-01-04.
But I could update later also without problem.
This time, after downloading, it says invalid zip file.
Do I need to pay for upgradation?

Hi Venkataraman,

You upgraded from version 7 to version 8 before the free upgrade time expired.
Minor version updates (e.g. from 8.4 to 8.5) are free of charge.

In your case, maybe the update package was not downloaded successfully.
Please try downloading version 8.5 from our website and install it again: