imho, there is no exact place where it should be stuck. but LTO requires that it should be stuck....

but since my car has superdark platinum tints sa windshield, hindi rin sya nakikita. but to comply with that requirement, what i do is to laminate first the sticker, and stick it on the windshield using scotch tape, para hindi natatambak ang mga old stickers. i remove it every year after registration.