Law / Motorbike registration / insurance in Poland, if I'm not living there [5]

Hi you all, my first message here :)

I'm thinking about to buy a used Harley from Poland (in Polish registry). Keep it in EU registry, but not take this now to my home country inside EU. The reason for this is the usage of this bike in central Europe, I like to fly somewhere there and ride around there, few times / year.

Now my question is, can I keep it in Polish registry, if I don't live in Poland, just visit there?

I know, I should have a registered address in Poland to do this, but what is this " registered address" in practice?
Is it just the address, what I write on papers there, my friends address for example? Then papers about this bike come there and he can send these to me.

Or does it have to be something more "official" ?