My opinion is that it is impossible to prevent sharing the resources to the public. If you add registration protection, than someone will start nulling this protection

That is the harsh truth - if you want to share it for free than go on but know that someone else will steal it from here and start charging money for your work, or will implement a virus in it. And if you have added credits to the resource and someone infects it with a virus than you will be the one who is blamed. And let`s not forget that even those resources are GPL still they have been developed by someone who tries to feed his family but you steal it from them and share it for free.
I personally have stopped sharing when back than I uploaded w.p.u.l.t.i.m.o which I bought for $500 and kindly asked not to be reshared, but exactly the next day it was widely available for sale on those nulled websites. Afterwards my license got banned by the developers.
There are people who do not respect others work and are short-term crooks. This is not going to change before the whole humanity evolve to its next version. Until than there will be no utopia, as currently good and intelligent people are like 20% from the mass.
So it is up to you if you are going to share here or elsewhere and help fellow developers not minding to see all those leechers, or you are going to stop sharing. But have in mind that if we continue share here things for free after some time everyone will know Babiato and people are not going to pay/download viruses from other websites. Everybody will come to Babiato.
So in conclusion you better work on the marketing your/babiato shares than thinking about how to protect those.