KeyIntersection

KeyIntersection[{assoc1, assoc2, ...}] generates a list of associations in which only elements whose keys appear in all the associ are retained.

Examples

KeyIntersection[{<|"a" -> 1, "b" -> 2|>, <|"a" -> 3, "c" -> 4|>}]
(* {<|"a" -> 1|>, <|"a" -> 3|>} *)

Please visit the official Wolfram Language Reference for more details.