the memes will be moderated before they go onto the blockchain to make sure it is appropriate content, but the memes going on the Blockchain will be submitted by app users only.
I can try to ensure this by requiring authentication from Facebook, Google, or any other suitable identity provider(s). I would only need some unique identifier to ensure that a person is who they say they are. I simply rely on this service to ensure that an account is a real person and not a bot.
I can create some ability blacklist users, so that if a user is found to be a bot or regularly posts inappropriate memes, the user and their posts will be marked as blacklisted, and the app will not display that content any more.
I could use Ropsten Ethereum and IPFS in Combination. This way the app would be free to use.
This way the list of memes displayed can be an immutable record of truly user generated content that would be available to everyone. All users will be able to look at memes and post memes from anywhere they can access the blockchain.
Once put on the blockchain the record of memes can not be retroactively censored because the blockchain would ensure that the records are distributed.
If you're have any questions, feel free to ask.
P.s. there is no crypto currency involved. This app is simply taking advantage of blockchain technology. This app in question will be available for free. Transaction on the blockchain will be on the free-to-use Ropsten ethereum blockchain, and image files will be stored on IPFS.