Now that Chrome has been updated to basically shame websites that are not secured, it would be good to have the option to purchase and enable HTTPS/SSL for any paid site since this is a best practice for SEO. I saw in another community post that there are no plans at this time to make this option available for anything below the Business package but I hope that is reconsidered if there is enough user support. Weebly is a great platform and keeps getting better, but it would be unfortunate to have to accept that using Weebly means that you will not be able to adhere to certain SEO best practices.
For reference, here is the post from the Google Webmaster Central Blog back in 2014: HTTPS as a ranking signal