The Celta Vigo forward, who cost a reported £7m, has penned a long-term deal with the Reds after centre-half Kolo Touré and winger Luis Alberto agreed deals to move to Anfield over the past month.
The Reds managing director is thrilled Liverpool have been able to move swiftly in the current window and hinted there could still be more arrivals at the Merseyside outfit.
“It’s fantastic, the third signing of the summer and very early in the window,” Ayre told Liverpool’s website.
“He’s a great talent, one that Brendan identified a long time ago.
“The scouting network and everybody else have done a lot of hard work to get him here and I’m pleased that we’ve been able to get his signature and have him in the squad.
“As we’ve always said, we’ve got our targets. We will work as hard as we can to bring them in. As we’ve said before, it’s always about getting the right players and the right deals for both sides.
“There’s a lot of work going on, there’s certainly no shortage of that. Hopefully we’ll have some more success.”
He added: “It’s always important. It’s not always possible but it’s always important.
“Particularly from the playing perspective, the manager and the coaches and all of the staff want to know that they’ve got the squad together, particularly ahead of pre-season.
“We’ve worked tirelessly, a lot of people behind the scenes worked ahead of the transfer window to identify those players that interest us.
“Then the hard work starts, negotiating and bringing these deals together.”