Stones was hotly pursued by Chelsea in the last summer transfer window.
Both players have been linked with exits from the club over the last two years after emerging as two of the brightest talents in the Premier League.
Stones in particular was hotly pursued by champions Chelsea, as they saw a number of big money bids rejected by the Toffees.
Moyes though believes that staying at Goodison Park was good for their development, but they must be qualifying for Europe and reaching cup finals to keep them longer term.
“In my opinion it was good for the development of John and Ross that they have stayed at Everton last summer,” he told the Daily Mail.
‘”I think Ross is having a much better season than he did last year. He’s playing well. I think John is as good a footballing centre-half as we have seen in this country for a very long time.
“Ultimately these players will want to play at the top level, so I imagine Everton will be desperate to qualify for Europe and want to get to cup finals too.”
While those two have been hotly pursued in the summer, it is likely to be striker Romelu Lukaku the Toffees will have to fight hard to keep this time around.
The Belgian has been in superb form all season and is currently the second highest goalscorer in the Premier League behind Jamie Vardy.
That has reportedly caught the attention of several top teams in Europe, who could all be keen to secure a move for him when the summer transfer window opens.