Write it down! Yes, I know you can keep track of the daily events on an app on your phone or laptop. Perhaps that works for you. I found that keeping a daily planner open on my workstation worked best for me. If a customer had a special tool they needed, I'd have a place to write down the information and to reference as a reminder.
I always enjoyed the follow-up. There would be many times I'd see the customer that next week and tell them, “Hey, I did find out I can still get parts for that old puller set you have.” It wasn't uncommon to have the customer respond, “I forgot I asked about that, thank you.” There's just too much that happens between the first stop and the last stop of the day. A planner is just another tool to assist you in providing excellent customer service.