Who haves the copyrights to assets from the asset store (I or my account)?

I'm no expert on the legal side of things so take the below as opinion rather than fact.

From a practical perspective, I don't think there would be any issue with doing that. However, the asset purchase is linked to the account you bought it from so if you intend to publish a game for public use (commercial or not) then you should only publish from the account you bought the asset from.