Digital copies should never expire. Why do they?

[Movie shy]

It was only in 2014 that I got a blue ray player and started buying Blu Ray's. Since many of my blu Ray's were released way before 2014 there are many digital codes that expired when I bought the blue ray. I feel there should never be an expiration date on digital copies. It seems unfair that I paid for the blue ray and it says a digital copy is included but more often than not it's already expired by the time I got the blue ray. We shouldn't be penalized by having some arbitrary date assigned and if not used by that date have it expire and lose out. When we buy a blue ray we can play that disc for as long as we have that blu Ray, why can't the same be true for digital copies? It seems very unfair.