My one only lasted about 6-7 years. It got really woody and had fewer blooms over the last few years. I don't think you can prune them hard.
I have heard they have a limited lifespan.

I thought they were likely to survive for less than 5 years. That's what my mum's one did, I haven't planted it.

They last up to 7 years or so depending on how you prune them in the first place. They will not shoot from old (brown ) wood only green so you have to prune them carefully right from the beginning. One cuts back by half everything which has flowered, once flowering has finished. This makes a lower growing bushier and longer lived plant. They are so easy from cuttings there is not point trying to prolong their lives.

My Mum's lived quite a bit longer than 7 years but it was very leggy and scraggy. I don't think she cut it back regularly though.

Mine survived 2 years, but it could have been the altitude and location. But I had a customer who had a one that i tip prund every year and it was 35 years old, but then he lived very near to the sea.