I just bought a 2015 ram 1500 5.7L hemi and the guy that owned for its first 44k miles ran 93. I've always stayed away from 93 so my ? Is can I run 87 or 89 now without having any pings or knocks or other issues?

 

I believe the engine was designed to run on 87.... fill it up, drive it, see how it responds.

 

my uncle always ran 87 then ran 93 one time and had pings that's what I'm afraid of

 

The PCM will eventually figure it out. If you want to reset it after you get gas, just disconnect the battery overnight when you get home. The PCM will forget everything it ever knew about how the engine runs, and will start re-learning from scratch. If it learns on 87 octane fuel, then it should run just fine.