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Using Asset Store Assets In Other Engines -- Is It Legal? - gamefromscratch.com
(gamefromscratch.com)
tl:dr
Godot: Does not have an asset store
Unreal: Assets made by Epic Games can only be used with unreal. Most other assets can be used anywhere, but check the license.
Unity: Pretty much the same as unreal. Assets licensed under the “Unity Companion License” specifically can only be used with Unity.