Password protection for your store is meant to be done by the technical abilities of the website where you have embedded your Ecwid shop.
Many CMSes provide a way to restrict the access to the particular page by publishing it for a limited group of users. And if using a custom built site, not relying on ready-built CMSes and blog engines, you can protect a particular page in a numerous ways, some most popular and easy of them described here: http://mashable.com/2008/05/03/5-fre...ct-your-sites/
Your site is based on Tumblr blog platform, as far as I can see. Unfortunately, Tumblr does not feature a way to protect just one page, but it allows to password-protect the whole blog: http://staff.tumblr.com/post/2679258...gs-it-just-got
Can you please clarify a little bit more, why exactly do you want to restrict the access to your store. With this information we may be able to find even better solutions to this.
Thank you for the reply, Eugene. The site is a blog for a california medical marijuana delivery collective. we need to password protect the store to ensure that only verified members of the collective have access.