"5 full days" between may 30th and June 3rd. Rift plans to go F2P fulltime.
This is a little treat for the current subscriber populace. Next month the switchover occurs. Soon enough it will be free-to-play for all. Monthly subs are so last MMO-gen.
Right now they operate Rift Lite for those who want a free taste of the MMO, but character progression is limited to level 20. It's scandalous shamelessly flirting with us like that.