Path of exile is another example. Many many years of new content, base game is free. You can buy increased stash size, which, while difficult, isn’t necessary, but massive QOL. You can also buy cosmetics.
Someone like me likes to support them for the hours I play, so when they release new context every 3-4 months and new leagues start, I usually buy something from them.
From travels to lots of hotels I’ve taken their mini bottles of shampoo and shaving cream, now from one hotel in Germany and another in France I exclusively buy those shampoos/shaving cream.