Should subscription games allow you to buy DLC? Loosing access on game expiry

[Signalstar]

No. Buyer beware. What you did was like buying new tires for a car you rented and then getting mad that you can't use the tires after you returned the car.

Maybe a warning could pop up letting you know that you won't be able to access the DLC unless you outright purchase the game once it is removed might be helpful.