Do Windows processes need Direct Memory Access?

I’ve just wiped my drive and reinstalled Windows. On my previous installation I let some stuff have direct access to the memory thinking that applications have got to go into the memory to run and I was getting overwhelmed with Defence+ alerts
I’m now thinking that they should be doing this by the operating system. Have I got this right? So does that mean you actually do have to let Windows processes have direct memory access?

Could I still have malware in the memory because of what I did in my last install? Any advice would be very much appreciated. I lost all my data, (back up yes I know) and the reinstall took hours.