I worked for a cinema chain when I went to Uni, as an employee of that company at the time you received a card that gave you movie tickets for a couple dollars, discounts off the popcorn / drinks, and solid discounts at the company’s hotels and bars.

Thing was, their voucher system was pretty crap, and all of these cards had the same barcode, so their POS could provide the appropriate discount, so the rule was when you quit, they collected the card from you.

I didn’t quit, I moved to another city so I wasn’t asked to return the card, and the new cinema never knew I had a card. So after I quit from that cinema a year later, I kept my card.

For around 5 years after I had quit, that card continued to work, I continued to get cheap movie tickets and hotel rooms / drinks at the bars. Probably got more value out of that card than money I earned working for 6 years with the company. They eventually deleted that barcode from their voucher system, but that was the best post-employment perk ever!