What I would suggest is that you contact elastic directly and there's people like me that'll work through details of whether an enterprise license makes sense with your volume of data and a retention... It may or may not.
Trying to figure this all out on your own through the documentation and discuss can be a little bit challenging.
There's a common confusion and it's understandable that cold and frozen and searchable snapshots are exactly one in the same... They are not
Cold and frozen are node roles and content tiers
What makes them valuable and cost effective is searchable snapshots which is and enabling technology at the enterprise licensing.
You can set up and use a cold node without enterprise licensing and it will work fine. But you will not benefit from the underlying value of searchable snapshot.
The true value is the frozen tier
I'll just put it that simply this way
A normal data node is size at 10 to 12 terabytes of either SSD or HDD.
With a frozen node in searchable, snapshots 100 TB can live on S3 and be accessed from a single node adding much much cheaper cost.
That is the value of searchable snapshots.
So quick question
How many terabytes a day do you think you're ingesting and how long do you want to keep them?
The lowest level of how searchable snapshots are created and stored is managed automatically in elastic cloud and if you were to do on prem you would need to have your own S3 storage and set up some proper ILM polices.
And of course, if you were going to do that all on your own, you'll be working with elastic sales and they would probably suggest a couple days of professional services.