For the longest time Reddit only supported media through external sites (Imgur, copy, etc).
Memmy (iOS app in beta) supports uploading media to Imgur and then inserting the link, much like Apollo did; hoping to see that extended to other hosting sites as well
Apollo did have a free tier and then a few paid tiers.
iirc, (I bought it many years ago), they had a one time Pro purchase that removed any ads and unlocked theming and such, and then the Ultimate which was a subscription to cover server costs of push notifications (although it did eventually end up having more features locked behind it).
While I personally did not go for the Ultimate subscription (didn’t really need the push notifications), I gladly paid for the Pro as it was well worth it IMO.