why does it say I havn't bought a game when I hav

I bought the sims 4 a really long time ago, and I'd occasionally go on to play. I haven't been on it for a really long time, but I decided to open it today, but it says I need to purchase it first. I've already bought the game online a really long time ago, so I don't have an activation code or anything, I just want to play the game that I bought.