The GiveLively donation widget may be used for carding (ie, testing stolen credit card info). These typically involve trying a series of small donations (like $1) possibly followed by somewhat larger ones.
This recently happened to my nonprofit, and we refunded the few donations that Stripe didn't block so that we wouldn't face possible chargeback fees later.
Since it's not worth it for us to accept a legitimate donation that small anyway, we'd like to be able to set a minimum donation amount (like $5) so that our donation page is less likely to be a target for carders.