Yes, you have snookered yourself.
Installing the FH V7 trial has overwritten all the FH V6 details.
So there is no FH V6 installation from which to retrieve your licence key.
You cannot revert to the FH V6 installation because you don’t know the installation licence key.
So you are now stuck on FH V7 and will have to ask Calico Pie to find your licence key as explained in the FHUG Knowledge Base for Licence Problems:
That may not happen until after the Christmas/New Year holidays.
It only works if you bought FH V6 from Calico Pie and not on a CD, in which case you must find the boxed set.
If you cannot find the licence key you will have to pay full price.