Hi Benedict
What I had to do was reload the last update that was performed before my S&U expired, so you should check to see when your S&U expired (I think you can do this on your account) and then reinstall the last update before this date, I think you can find the previous versions of Pix4D on the support pages here, although it is not easy. or alternatively tell Pix4D on here when your S&U ran out (this is what I did) and they will hopefully be able to help you
some information bleow
https://community.pix4d.com/t/3345-Previous-version-of-Pix4D-Windows
https://community.pix4d.com/t/3822-How-to-downgrade-the-version-of-a-pix4d-file-