Urgent/TimeSensitive End-o-subscription last min plugin shopping Qs!

Hi All!

Happy Hols!
So hand in air, yes, I've left things til the 11th hour and need some guidance.
I've been running so hard this year I've not taken a spare moment to reap the benefits of my subscription.
– My subscription sometime on the 24th (dunno if that's midnight where? etc),
but I need to know in practical terms what that means for last min plugin snagging?
Will plugins I get still work once my subscription expires?
Do I need to activate it on my site before that happens, say with my API key?
Super Quick response / insights appreciated as time's of the essence and truly not on my side… I m a y only have as little left as 90mins!

Many thanks! : ) and happy holidays!

P.s. if whomever responds has their top 3-5 don't miss selections, that'd be a bonus!
º<§:^{)§ <- santa smiley!