Changed the Staging and Production url in license manager. Verified it is X license ( I have some pro licenses in there also). Pasting the Themeforest purchase code in wordpress admin gives me "Your code is valid but looks like it has already been used on another site. You can revoke and re-assign within your Themeco account.".
Doing this on local staging machine, which is not reachable to outside, as current production site is not using X. Wouldn't think that would affect it.
Other info that may be valid. Installed X version is 4.6.4 ( started on a LONG time ago and the project got put on hold ). Was registered license at some point but don't know which one.
Client is ready to go now and so trying to just run update on the old project and use an existing license that is no longer in use. Wordpress update worked surprisingly, but can't get X to update because validation is failing.