You need to login with the account which purchased the file and then download and check the documentation for the theme that will cover this.
Anything beyond this you can ask the author of the file, but again it will need to be using the buyer account so they can verify your purchase
On the whole you will always need permission form the authors and potentially extended licenses etc.
The best and safest way to do this is to ask the author individually per plugin (only the really big ones like Revolution and Layer slider have made these changes to simplify it that I am aware of).
Only assuming you have permission from he original author of the plugin.
As such a high % of themes on here use Royal, Layer and Revolution slider these three have altered their inclusion rules for themes e.g.
The author’s support forum for this theme is here http://herothemes.com/support/?envato_item_id=6217061
Support can take up to a week to reply. You can try tweeting them otherwise
That link is simply not good enough to be for sale here so you wont find anything just like it.
That said you could easily achieve this style using one of the many page builder and multi purpose sites (you could even find something nicer!)
I do not even see that theme still for sale here now. I think you will be lucky although if you remember the author’s name you could try emailing them. Good luck
Cant be validated – check your code
Logo needs to be clearer
Spacing/margins could be improves
probably needs more to it
Generally i think its cool – I think the video could be housed in a skinned player or something to make it look cooler , accordion tabs look a bit placed and small in the middle on their own and validate some of the avoidable issues