If it's been more than 6 months since you bought Pro, your email address won't be in the database anymore

If you originally bought from a scam site, I've got no idea how you were able to get a Pro version from the official site!

If you want to purchase Pro again, make sure to go to the official site www.limewire.com Pro will cost you $18.88 & includes 6 months of free updates & email support.
You should be able to enter details for any credit card - old or new.

Depending on how old your previous version of LW was, you might see a lot of difference in the current version of LW. You might be better off trying out the free basic LW first. That way, you can see how the new version works, if you like it then think about buying Pro