When a lease or contract does not define a term, the law looks to its common, everyday, or plain meaning. "Utilities" generally means water, sewage, electricity, and heat (e.g. oil, gas, etc.). As commonly understood, it does not mean a security system. If the lease only required you to pay utilities, you should not have to pay for the security system.However, the language you quote is not limited to "utilities": it states "utilities and/or services." "Services" is broader than utilities: it can include any non-utility services provided to the home or leased unit, including, for example, potentially cable TV, internet, and also the security system and the attendent monitoring thereof. "Services" as commonly understood could certainly include the security system. Therefore, based on the broader-than-utilities language you cite, it appears that you do need to pay for the alarm system.