When do players retire?

Do players only retire when they are old and their contracts have run out or can they also retire with e.g. 2 yrs left on their contracts?

I added Ewing to my dynasty and he should not retire after a year.

It depends on the age basically, they still can retire when they have e.g. 2 yrs left, so basically if you put his real age he will like 99% retire, unless you change his age

Once a player has reached the age of 32, he's more likely to retire especially if his ratings are in decline. Retirement is generally more likely after the age of 35, sometimes the years remaining on a player's contract are an indication of how much longer he intends to play (especially if he's just signed a new contract) but that isn't always the case. An aging player may retire before his contract is up (but not during a season).

Thanks. Is it only age or also experience? (years pro)

It seems to be a combination of both, though generally speaking players in their mid 30s have over a decade of NBA experience anyway so it tends to go hand-in-hand.

Do you think that Ewing will definitely retire after the first season?

Hard to say, sometimes the game will have players retire after they turn 32 and other times they won't. If you reduce his years pro and change his date of birth so that he's younger, it should prevent him from retiring after the first year. You might want to change his CAREERPKG to 2 or 3 as well as an added precaution.