Social media escrow idea

Hi gang,

I have been lurking in these forums for quite some time. I have noticed that quite a few recently interviewed startups acquired first few users using lifetime subscriptions so that got me thinking about early stage marketing tools.

Do you guys think that creating a small SAAS that allows business owners to create some contract (e.g. if you submit a tweet or an instagram post with this particular hashtag or this URL then I will grant you 1 month free subscription to all premium features) and making sure that the posts are not deleted or modified would be useful to anyone? I imagine it would be useful for early traffic and SEO.

Cheers,