Purchase problem

If you had previously signed in with Facebook, and still have access to the email address your old Facebook account used, you can try using password reset at www.adobe.com to regain access to your original account with the Lightroom subscription.. This will allow you to sign in with that original email address plus a new password you set, without going through Facebook. 

For help with this, please contact Adobe Support at https://helpx.adobe.com/contact.html?rghtup=autoOpen
...and in the chat field (lower right), type AGENT

Adobe Support may be able to help you switch your existing, paid Lightroom login to another email ID.  

If you don't have access to that original email anymore, yes, you will have to wait until the current subscription lapses.  Maybe even waiting 7 days beyond that (there might be a grace period).  After all that, then I think your iTunes ID should be able to start a new subscription for another Lightroom account.  Your iTunes ID can only subscribe one Lightroom Mobile account at a time.

contact apple if that's whose app store you used.