Maximum RAM Usage refers to the maximum limit on the total amount of physical memory used by the virtual disks created by Primo Ramdisk. Total memory usage includes memory used by RAM-disks and hybrid-disks. Taking the Professional edition as an example, its Maximum RAM Usage is limited to 32 GB, then it can create multiple virtual disks with total memory usage not exceeding 32 GB, such as one 32 GB RAM-disk, or two 16 GB RAM-disks, or one hybrid-disk with 1 TB capacity but using only 32 GB RAM, and so on.
Maximum RAM Usage is independent of the total amount of physical memory installed on the computer. There is no limit to running each distribution, regardless of how much physical memory is installed on the computer.