You could also avoid "hence", which is better used in literary or journalistic works. Some alternatives:
Yes, I am aware that your company is not operating this system anymore, but would be most interested in past/historical data, so I contacted you.
Yes, I am aware that your company is not operating this system anymore, but would be most interested in past/historical data, which is why I contacted you.
To my US English ear, the word "hence" sounds archaic/awkward if not used with a noun phrase as in Merriam-Webster's website
Panforte—a cross between a cake and a candy—is a classic Italian Christmas treat. It's a very dense, rich confection loaded with nuts, dried fruit, and spices (hence its name, which means "strong bread").
In the past, the playoffs lasted five rounds, but the MHSAA is doubling the size of the playoffs, hence the possible need for an extra week.
I don't have an authoritative source for this preference (noun phrase rather than clause) but it's an anecdotal assessment based on what I've read over the years.