In an individual server report, "Peak/Min Memory" is free memory, whereas "Peak/Min Memory In Use" is memory used. They are essentially the opposite of each other.
The blue line describes “Peak/Min Memory In Use". "Peak/Min Memory" is in pink.
If your "Peak/Min Memory In Use" is 1010.73, you have 13.17 left to use, or ~1024.
Likewise, if your "Peak/Min Memory" equals 299.63 left, you used is 724.24, or ~1024.