question about numbers of client

hello,

i have a sophos utm120 rev 5 and a home edition license.

i heard that home edition can handle 20 clients.

i have confusion that it meant can handle 20 clients 'at the same time' or can handle 20 clients that f/w remembered.

for example of latter, it can handle 20 clients' mac address. and if some other client want to connect f/w, f/w refuse to connect.

it's important for me that i have some vm.

sorry for broken english.

sincerely,