Dear All, I am using a Membership sig up: "The most

Dear All, I am using a Membership sig up:

"The most powerful, easy to use and flexible membership plugin for WordPress, Multisite and BuddyPress sites available. Offer downloads, posts, pages, forums and more to paid members. Version 3.4.4.1 | By Barry (Incsub), Cole (Incsub) | View details
There is a new version of Membership available on WPMU DEV. View version 3.5.2.4 details."

Two questions:
1) I cannot update top the new version and I am mot sure why.
2) I get a lot of spam signups. Is there a way to eliminate these with a built in Captcha or something like that?

Thanks.

Imre