Can I still use old V5?

Excuse me, I'm curious about the use of old V5. I understand that technology evolves rapidly, especially in the cryptocurrency and finance sector. However, I've been using V5 for quite some time and it's been serving me well. My question is, is it still feasible or advisable to continue using V5 in light of the latest advancements? Are there any known security risks or limitations that I should be aware of? Your insights would be greatly appreciated.