Unable to register licensed copy of LR3 on newer Mac

I recently moved off my old MacPro to a newer machine running Mac 10.12.6. LR3 installed fine. I entered the original LR2 key and the LR3 key, both products purchased from Adobe. When I go through the registration process I get a return message that registration failed (which is likely due to the fact that the page for the LR3 product registration no longer exists).

LR3 suits my needs fine, but as best I can tell when the 30 trial that the installation has me in expires, I am up the creek. Given that I am retired and on limited income now, updating to the new subscription model is not practical.

How do I get my legitimately purchased LR3 registered so I can continue to use it???

Ted

(BTW, when I installed PSE8 on the newer machine, I got none of this registration issue blow back.)