All licensees must notify, in writing, the licensing authority that issued that license, the Chief of Police into whose jurisdiction the license holder moves and the Massachusetts Firearms Record Bureau of any change of address. Such notification shall be made by certified mail within thirty (30) days of the move. Failure to do so shall be cause for revocation or suspension of the license.
A Change of Address Notification Form is available on mass.gov website.
https://www.mass.gov/eopss/firearms-reg-and-laws/frb/firearms-forms-and-applications.html