one of my clients was using an unauthorised egineering software and recently got a legal notice by email from the owner of that software. My friend deleted all softwares from all systems. What else he can do to safeguard his interest ?

He has to reply to the owner with the assurance that the software has been deleted.

Even if he delete it from system, and gives assurance, the other party can ask for remedy such as account of prifit, damag  . But some hackers use false IP address and MAC address for time being for the same situation.

Even if he delete it from system, and gives assurance, the other party can ask for remedy such as account of prifit, damag  . But some hackers use false IP address and MAC address for time being for the same situation.