clip test will tell you the stock's condition as others suggested. alternatively you can shoot a small test roll of it, maybe 15m or so, if you are processing other films soon and can include the test to the same batch. that will show you the overall quality you can expect from the stock in your project and if you have to take elevated grain etc. into account.
old film usually has elevated base fog and the sensitivity may be little lower. I tend to overexpose all old stock by about 1 stop (5 - 8 years old) and it usually works very well. background gamma radiation may sometimes be a problem with very old stocks, it happens at about the same rate even with frozen film so one can't store the cans forever, though long times are of course possible. you can also experience colour shifts with old film but usually nothing so extreme that it can't be corrected rather easily in grading.
most of the time I purchase all films over 200 ISO new because it is easier to see the age and storing conditions with them, especially in smaller formats. storing a 500T film for several years is not ideal I think, even if it's 35mm. but if you have something like 50D it is not a problem at all