Question about the free 3-month offer with any pass?

[FBarnhill]

The offer ends at 4/8. But do I have to use it by then or is that the last day for me to purchase it? And if the latter, when is it the last day for me to use it? Earlier, I heard I need to use it by July 31 but I can't find the info anymore.

 

[Parkscope Joe]

Last day to purchase. The pass becomes active once you enter the park.