Hi,
If it's a 500 VA (Volt Amper) type UPS it will last (on the average) 4-5 years than you'll have to change the batteries and it will last another additional 4-5 years.   If it's a 1000 VA (Volt Amper) type UPS it will last (on the average) 5-6 years than you'll have to change the batteries and it will last another additinal 5-6 years.  We use only APC (that's the name of the producer) UPS's (some 50) and have outstanding experience. 
Best regards,