The phrase "unlimited winks" means that there is no limit or restriction on the number of winks someone can give. They can wink as much as they want without any restrictions. Full definition
The upgraded membership allows you to communicate freely using their email service, send unlimited winks as well as virtual gifts. (straight.sex-dating-reviews.com)
It includes extra features such as unlimited winks, access to chat rooms, access to forum, hide profile picture, and so on. (lovelogger.com)
Users sign up for free, but if you pay for a subscription to Zoosk, you'll get unlimited winks and messages, full access to the ZSMS feature, can see who has viewed your profile and you can chat with the connections you make. (huffingtonpost.com)