Use LR 4 instead of the CC version

Hi.

Years ago i bourght the LR4 as a stand alone program

The LR CC came along, and I jumped on to that, with the photography plan.

Now I no longer needs Photoshop, and I have cancelled my Photography plan with adobe.

I wanted to go back to using LR4, but it seems I can't.

How can I use the old LR4? I have the key and Adobe has regitered it to my account, but i cant get it to work.

Best regards