Manager Sean O'Driscoll said: "Playershare have made the funds available to enable us to bring in James.
"James is a player we have watched and identified as one we would like to bring in.
"He has a good eye for goal and is developing and improving all the time. I don't know how many times I've said this over the past few seasons but, we are again indebted to the hard work and fundraising of Playershare".
Keene added: "It's a good club with a professional set up and they have started the season pretty well.
"I'm looking forward to the experience of playing for Bournemouth and hopefully I can do well."