I had a quite high end Android phone from Sony 3 years ago but because it's dual SIM version I maybe receive only one update. I'm running Android 5.0.2 already

I had a quite high end Android phone from Sony 3 years ago but because it's dual SIM version I maybe receive only one update. I'm running Android 5.0.2 already for 3 years now. My phone works still well but who can count the vulnerabilities I have now on my device...