Hodgson could decide to sell the Holland international in the January transfer market.
The 23-year-old was being linked with West Ham and Tottenham this summer.
“The thing about Ryan is that for three years here he has not had much of a look-in,” said Hodgson.
“He was brought into the club with a lot of pomp and ceremony after winning the European Under-21 Championships. I saw him play several times because I was working for UEFA at those Championships and he was the player who was being chased by clubs all over Europe at that time.
“Since coming here he has not fulfilled that potential, hasn’t had the chance to. So when there were offers for him (in August) we were prepared to allow him to go down and speak to those clubs. But we made it perfectly clear that other things would have to slot into place before we were able to allow him to go.
“The other things we had in mind did not slot into place and now it is up to him to convince me. No doubt if, by January, he hasn’t succeeded in convincing me that he is the player we need then he will have to accept we will be in the transfer market for a centre-forward once again.
“But at least he has this period of time. He is working very hard, he is very determined to take this chance he has got, so that last-minute transfer thing was perhaps something we will all be glad did not come about.
“In the meantime, we will have the chance to do our thorough scouting so if money was available (in January) we would be able to look into the situation again.”
