Now suggest installing version 10.49, which shouldn't ask for registration as it's within the six-month gratis window. 10.48, had a speed change bug.
You will never be required to pay, or to upgrade. And unregistered trial or free versions can always be tested. 10.96 would prompt for an upgrade, but it still might function on a trial basis. Of course, retain your original installer and licensing info, should it be needed. If you revert to 10.49 it likely will be automatically registered.