So I have installed PSE 15 and gave the serial to the software, but I cannot use it without signed in. How do I use this software without online/signed in? I want to use it only local and without an nternet access. When I signed out from the software, it won't start and ask me to buy it or use licence. I had to sign in again and give the serial number again.
You should not sign out. Just stay signed in and you will be able to use it even when not connected to the internet.