Questions about Licensing and Youtube

Okay, so, heres my… problem.
I have found a couple after effects packages that include transitions, text animations and effects etc, and I’m not really understanding what envato means about the “single end product”.
I’d like the begin making youtube videos and I have my logo and everything (designed and made myself) but I wanted to add a splash animation to it to give it a bit of a “pop” I guess.

But since it’s a youtube intro (ie. it will be in every video I make and post) can I purchase the regular license and use it? Even if I choose to monetise my videos in the long run (with adds)?

And I heard something about needing to purchase licenses every year or so???

Also, with the transitions and stuff like that, are they fine to be used in my videos in the same situation as above?

Thanks for the help!