The striker joined Albion from Everton last summer.
"I was at Everton for a very long time and making a big change like that is always going to be difficult.
"But in life you make decisions and take on new challenges and I am in for a different challenge now.
"I'm happy. I never regret things that I do. West Brom is a really good club with a good fanbase and a good set of lads as well."