I decided NOT to have an emergency buzzer, which has to be continuously paid for. Also, with those, if pressed, the company then just calls your listed contacts.
I have alexa in my flat, and wear a smart watch, purchased by kids as a pressie, so am in constant contact with that. In the event of my requiring assistance, I can just call out for Alexa to telephone my daughter or SiL. The call then goes direct to their numbers.
My daughter, keeps her phone on silent when working in class, but also wears a smartwatch. She knows that if there was a call from me during working hours (which she would see on that watch), it would mean an emergency and would answer it.
No on-going costs are involved, and both she and I feel a sense of security that I can make virtually immediate contact. Only real problem would be if I was actually unconscious - not sure how to cover that!!!