I had to check and according to the Sports Reference site Hill has indeed signed his 8th contract with Boston:
June 30, 2010: Signed as a Free Agent with the Boston Red Sox.
November 6, 2010: Granted Free Agency.
December 16, 2010: Signed as a Free Agent with the Boston Red Sox.
December 12, 2011: Granted Free Agency.
December 13, 2011: Signed as a Free Agent with the Boston Red Sox.
November 30, 2012: Granted Free Agency.
February 1, 2014: Signed as a Free Agent with the Boston Red Sox.
March 24, 2014: Released by the Boston Red Sox.
March 26, 2014: Signed as a Free Agent with the Boston Red Sox.
July 1, 2014: Purchased by the Los Angeles Angels of Anaheim from the Boston Red Sox.
August 14, 2015: Signed as a Free Agent with the Boston Red Sox.
November 2, 2015: Granted Free Agency.
December 1, 2021: Signed as a Free Agent with the Boston Red Sox.
November 6, 2022: Granted Free Agency.
August 17, 2024: Signed as a Free Agent to a minor league deal with the Boston Red Sox.