I’ve been working on Oku for a while, which is a reading companion app (think tracking, reviews, book discovery, friends) and we're monetising it with a freemium model where members can pay for additional features. We have two paid membership tiers: premium and supporter.
What’s probably a bit different is how we’ve structured those tiers. All of the additional features we offer are available in the cheaper premium tier, but when launching our paid memberships we decided to add a more expensive tier. While it does give you early access to new features and a small badge on your profile, we make it pretty clear that the main benefit is supporting us more!

Before we started charging for premium memberships we’d often get emails and tweets from people that wanted to pay or support us, and the goodwill we felt from people that were really excited and supportive of what we were doing is what prompted this experiment.
Well, we’re sitting at around $450 MRR at the moment so we’re not making enough money to support anybody going full time yet. But 34% of paid members opt for the more expensive supporter tier (on what is already a fairly expensive product), which ends up accounting for just over 50% of revenue. We also see that 83% of current customers have gone for a yearly membership, which we offer a 30% discount and has obviously been very helpful!
Now obviously this is not going to work for every product. As I said we had a particularly excited group of initial members that were begging for something to replace Goodreads with and were really happy to support us. Turns out people like supporting indie products, especially when the competition is Amazon!
But I'm interested to hear if anybody else has tried anything like this and how you got on with it? I don't think I've really seen it done before, but maybe it's worth thinking about!