Four players will be leaving MK Dons once their contracts expire at the end of June.
Meanwhile, manager Karl Robinson is due to meet with out-of-contract trio Carl Baker, Cody Cropper and Alex Revell to discuss their futures.
The Club will also be meeting with young goalkeeper Charlie Burns, while fellow Academy players Ben Tilney and Giorgio Rasulo have both had their one-year extensions in their contracts exercised.
Jay Emmanuel-Thomas, Jake Forster-Caskey, Rob Hall, Kevin Long and Josh Murphy have all left the Club following the expirations of their loan deals.
Kay, 33, joined the Dons on a free transfer in July 2012 and made 161 appearances during his four-year spell at stadiummk.
He featured more times than any other player in 2014/15 (49) and helped to keep a Club record amount of clean sheets en route to achieving promotion to the Sky Bet Championship for the first time.
Right-back Spence moved to MK1 on a permanent basis in August 2014 having enjoyed two successful loan spells with the Dons during the 2013/14 season.
He played a pivotal role in the Club’s ascent to the second tier and leaves Milton Keynes having totalled 111 appearances.
Former England international Upson was brought in last summer but, due to injuries, was limited to just seven appearances in a Dons shirt.
Emmanuel-Thomas joined the Dons on loan from Queens Park Rangers on Deadline Day and featured four times for Robinson’s men.
Midfielder Jake Forster-Caskey enjoyed two loan spells at stadiummk during the 2015/16 campaign, totalling 23 appearances. He will be fondly remembered for scoring the winning goal in the Dons’ memorable victory over Derby County with a superbly-taken free-kick.
Hall was signed on a season-long loan back in July after impressing during the promotion run-in last campaign. He made 32 appearances for the men from MK1 in 2015/16 but his spell was cut short by a serious knee injury.
Defender Long was brought in mid-way through March to provide depth in the defensive positions. He had to wait until the penultimate game of the season to make his first appearance, while he also started the season finale against Nottingham Forest.
Murphy enjoyed a superb season with the Dons, after joining on a season-long loan from Norwich City. The winger scored seven goals in 46 games and was named Players’ Player of the Year by his team-mates.
The Club would like to thank all those players departing for their contributions and wish them every success for the future.