Using the netdata systemd memory chart and filtering for just RoonServer, this is what I see over the last two days:
You can see two instances of additional memory being used at 4 AM with some (but not all) released about 3 hours later.
My Roon memory usage does increase with time and/or Roon use but it does not increase to the point that I have to restart the service (or the server). This may be because of the limited size of my library.
Note: my Roon usage over the period shown has been exceedingly limited due to other demands upon my time.