How would you do it?
First I’d learn to code 😫 Failing that I’d give the idea away for free and somebody would host a server where you could store your memes against your npub for a fee. If you want a private store you could pay a small fee. However, you could also make them public and other npubs could pay a small fee to download them and use them. It would need to be very searchable, which is where the hard work coding would come in.