Methods, systems, and computer readable media for using variable metadata tags. A method occurs at a metadata processing system for enforcing security policies in a processor architecture. The method comprises: receiving, at the metadata processing system, a tag associated with a word in memory, wherein the tag indicates a memory location containing metadata associated with the word and wherein the tag length is at least in part determined using tag usage frequency; obtaining the metadata from the memory location, and determining, using the metadata, whether the word or a related instruction violates a security policy.