The 22-year-old Spaniard spent six years at Anfield but failed to feature for the Reds on a regular basis.
He spent loan spells at Norwich, Atletico Madrid, Rayo Vallecano and Huesca.
Pacheco made five Premier League appearances for Liverpool during his stay - but makes way following a busy month of new signings under Brendan Rodgers.
Rodgers has declared himself happy with his side's transfer business and plans further signings in January.
He has brought in eight new players this summer, including three in the shape of Mamadou Sakho and Tiago Ilori from Paris Saint-Germain and Sporting Lisbon respectively and Victor Moses on loan from Chelsea on deadline day.
"We've done great business over the course of the summer," said Rodgers. "We'll run with that until January and see where we're at then."