For your general question, the answer is it depends. It's best to add the comma only when the comma helps the reader to understand the sentence.
In your particular example, I think the comma does help with comprehension. Without it, there is the risk that the reader will think that the clause The Tenant hereby sublets to the Subtenant stands on its own. The second comma loosens the coupling between and the Subtenant agrees to take and the premises of Lot No. 7, and makes it easier for the reader to spot that the first and third clauses should also be joined together.