a euro will tell when & what each fault is via its log
you can ignore or neglect your alarm & it will start beeping in the middle of night & piss you, your family & anyone you contact about undertaking a repair as its Christmas & we've already had 48 weeks of more of dealing with dickheads who spend 100's of thousands on a house & never have the common sense to get the previous owner to have the alarm serviced before they take possession of the property or think that anytime in the future it might be prudent to have the preventive maintenance done.
or for less than £130 you can just buy some new controls
https://www.securitywarehouse.co.uk/catalog/intruder-alarm-c-36/security-control-panels-c-36_102/lcd-remote-keypads-c-36_102_107/scantronic-ion-keyk01-keypad-p-3776.html
https://www.securitywarehouse.co.uk/catalog/intruder-alarm-c-36/security-control-panels-c-36_102/110-input-zone-small-c-36_102_101/scantronic-ion-10-zone-alarm-control-panel-cw-keyk01-ion10k-p-5928.html
go back in time, subscribe to maintenance contract & ensure the alarm co do the routine replacement of primary batteries ?
I'd say every 3-5 years for a siren, c sized lithium things with a wiring loom,