Hi Ron,
I believe you'd have to purchase licenses for the additional controller. Not sure what you mean by "off lease pulled unit", but my guess is it's out of support? If so, that might bring more issues. I think your local NetApp representative/partner would be in a better position to inform you what options are available, but my experience with EOL systems is that NetApp generally don't want to deal with them under any circumstance other than supporting already existing systems with valid support contracts.
Good luck!