A Guest Pass allows non-citizens of Romerus City to enter and stay in the city for a maximum of 7 days. Anyone with a Guest Pass can move freely between the districts, but once their Pass expires they can be arrested, fined, or thrown out of the city and banned from returning. You can renew your Guest Pass on the 7th day for a small fee that compounds with each renewal, up to a maximum of 10 renewals. After that, you cannot return to the city for 70 days unless you apply for citizenship.
The Guest Pass is not an actual physical object. Instead it is attached to a person's identity, as are many things in the world, such as bank accounts. Enforcers can check if a person has a Guest Pass by doing a brief retinal scan.