Moveable is the older spelling of the adjective meaning capable of being moved. But movable is now the preferred form in all main varieties of English, and this has been so for over a century. The preference extends to derivatives such as immovable and movability.
Both words are accepted, however. On the web, movable appears about three times as often as moveable, and this ratio is roughly borne out in recent books and in current news stories from throughout the English speaking world. British writers tend to use moveable a little more often than the rest of us, but they still prefer movable by a significant margin.
This ngram graphs the use of movable and moveable in a large number English-language books published in the last two centuries. It shows the switch from moveable to movable occurred long ago, though, somewhat interestingly, moveable has stayed steady while movable has declined.
Both spellings are easily found in sources from throughout the last few centuries: