Re: Lost product code for simcity!
Hi @MathiasDK1234 - If you registered the code on a different account, you won't be able to reuse the codes on any other account. Since you can't remember which email it was registered under, you will probably need to contact EA to have them help you recover the account, and then they can merge / move the old registration to your current account.
Account recovery form (you'll need to log in with your current account to use)
Changing emails on accounts - to link two accounts when one has no games on it
Merging two accounts - to combine two accounts when both have games registered
You could try logging in at EA.com with different email / password combos to see if you can find the old account. If you discover it, it would be easier to change the email on the account, but you could only do it on your own if you have access to the old email addresses. If you don't, you'll still end up having to contact EA.
Be aware that because of the current pandemic situation, there have been some temporary changes to EA help & support. Phone support is closed and support hours are reduced to 8:00 a.m. to 11:00 p.m, UTC Monday - Saturday. You can contact them on Twitter or Facebook 24 hours, too. https://answers.ea.com/t5/EA-General-Questions/IMPT-Support-Options-Update/m-p/8864042#M334946