There is some confusion among New York City motorcyclists and scooterists about how to legally park (e.g. avoid parking tickets) at a muni-meter. Some think that motorcyclists should pay and attach the receipt to the bike, others hold that one should pay at the muni-meter and hold on to the receipt in case a parking ticket is issued, while others claim there is no need to pay at all.
According to the DOT, motorcyclists must pay at muni-meters AND display the receipt on on the motorcyclists:
Like other motorists, motorcyclists using Pay and Display Muni-Meters, must display their receipt on their vehicle. To prevent theft or damage to the receipt, DOT recommends using clear plastic holders attached to the motorcycle with a lock or other mechanism. Devices made especially for this purpose can be found in specialty stores.
The locking mechanism pictured above seems a little ridiculous. But, if you really want one, you can purchase a locking parking permit holder from Login Parking.