add permissions for iTunes/drm music from old Apple account

I'm restoring data from a backup drive, after I had a hard drive replaced at an Apple store.

For some songs, I'm getting prompted to enter the password for an Apple ID I haven't used in years. (One linked to an old email account.) To be clearer, I've only ever had one Apple account, but at some point I changed the username and the password. I have no idea what the old password is, and the old email address no longer exists.

How can I restore permissions for these tunes -- and maybe terminate permissions for old, dead Macs--to my current i.d.?