You didn't clarify anything. But I will. Provided you were 21 and already had an FOID so you could legally buy a handgun in 1986, you could register a handgun and keep it legally provided you pay the fee to re-register it every year since then. That means that a currently 41 years old or older, handgun owner, that has continually maintained their FOID, and paid the fee every year in order to keep his handgun registered at the local police department, can now still legally possess a handgun in the city of Chicago. Sounds pretty communist doesn't it?
Not to mention, the gun registration was a grandfather clause. So if you moved away, then tried moving back, you could no longer register the handgun because there was a break in the registration process.