How can I understand if my landlord is using the internet I'm paying for..

I am NOT talking about wireless...So, to clarify my question, if she
just buys a modem from a store( I don't think she is stupid enough to
rent one thru the cable company since I'll see it on the invoice) and
hooks it up to her computer (since she has the tv cable going to her
room anyway...) How can I understand if she did this or not? Please
don't  tell me to unlock her room and look in it... :) Thanks.

Ask the cable company to check? They must have ways to tell.  The phone company
could tell muliple use with simple measurements. Bet the cable company same.

If your computer has gotten very slow there may be a dozen other reasons.

thanks red, however;I can't call the cable company and ask because the
bill is on her name.

Hello Mastertrg,

You don't indicate the cable supplier / city, but based on what I've seen

 - the cable company requires a cable modem for each computer / router
 - each cable modem has an unique MAC address - which must be reported
to that cable company
 - the cable company downloads software to the cable modem by that MAC
address, allowing it to work
 - [conjecture] the cable company will only download to one cable
modem unless it gets paid for the extra connection

Since you don't see a second cable fee on the invoice from the cable
company, it is highly unlikely the landlord is using the cable
connection.

  --Maniac

I'm sorry but the answers just don't satisfy me. I needed to know some
kind of program that would show me the users on my network or
something, idk ? :?:
Anyways, thanks for the comments.