You could get a ticket for no registration sticker even if you have paid the registration fee. Because it is required by law to affix the sticker. If you paid ur registration fee, but didn't put the sticker on, the fine would probably be just the processing fee for the ticket. If you didn't pay, you will certainly be fined by the court, along with DMV registration + a % of the registration for non-payment.
Tickets are issued to the vehicle's registered owner when driver could not be identified