It seems you are saying that you saw some assets in the unity store, but then found them elsewhere using searches, and want to know if it's ok to use them?
If this is the case, then I would say the answer is a resounding no.
When it boils down to it, the choice is yours to make, but it is obvious to anyone that unless you create the assets, or purchase them, or find some free assets, then you could be on dodgy ground, especially using assets 'found' on the net.