The winger was sent back to his homeland as part of the deal that brought Marcos Rojo to Old Trafford last August.
A return to Sporting – where the Portugal international started out – appeared to spell the end of Nani's United career, even though he only signed a new five-year deal with the Premier League club in September 2013.
But the winger is adamant that he can force his way back into the United first team under Louis van Gaal.
When quizzed on whether he felt aggrieved with Van Gaal for sending him out on loan, Nani told BT Sport: "No. Because the club know my value and I know they want me to stay.
"It was me who made the choice to leave the club and it was a good decision by me because I knew if I stayed one more season at Old Trafford, it would be very hard for me."
Reflecting on his return to his homeland, Nani added: "I just need someone to believe in me, trust me and my qualities, and give me an opportunity to show them on the pitch.
"It's an experience I wanted a lot and needed as well because the last two seasons at Manchester United I had so many injuries and I was very upset with a lot of things that happened to me.
"I was missing my family and friends and I wanted something new. The only opportunity I had to be happy, and Manchester United to be happy as well, was this one."
