Thank you! Can you keep these tickets for a future visit or must they be used on that trip? How long are tickets good for? TIA!
As long as they are never used (put through the turnstyle), they'll be good forever. Once they are used, they expire in 14 days. I still have several old park tickets left from when the requirement for free dining was one day park tickets. It seemed like I was always going more than once during the free dining times, so just accumulated tickets. They only allow you to use one of those tickets per year when you get a new AP though, so I am still using one a year every time it's time to get a new AP.

I haven't used free dining since the requirment went to two day park tickets, so hopefully will run out of those old one day tickets in the next few years.

If you do keep those tickets for a future trip, just remember to use them to enter a park first, then go to guest services to upgrade them to what you need (so that you will get the current value from that ticket, instead of what you actually paid for it several years before).
If you want, you can go to any guest services to have those two day tickets taken off your room key. They'll give you a paper mylar ticket that just says 'two day MYW ticket, not for park hopping' on it. You don't have to though. I know this past Nov, I just used the old KTTW room key that mine was still on. Even though the date on the room key was from several years ago, the turnstyle still took it. I then just went straight to guest services inside AK and had them upgrade it to a new AP. It expires one year from that date.