Current implementation has the following limitations:
Maximum object size: 65534 keys
The order of object keys is not preserved
...
These limitations may be lifted by using more bytes to store offset pointers and counts on binary level. Though it's hard to imagine a real application which would need that.
There’s one case where it gets super popular, or attacked by spammers/bots, and the site becomes more effort to operate publicly than you want to do for free.
In another case your girlfriend stops using it, as well as some family, and the continued maintenance over the years feels like it isn’t worth it (because there is always maintenance.)
Either way you might want to shut it down, and promising “forever” to users feels problematic when you’re not being finically incentivised to keep it running. With the financial incentives it’s much easier to pass the burden on to someone else if you can’t run it for whatever reason too.