With $975 License value, you have 25 separate licenses. After all: 25 x $39 is $975
How you use it is up to you. Suppose you have a team of 6 people, 1 in the office and 5 in the field. This makes 6 users in total.
If you have 25 licenses in stock, you can get four months ahead: 4 Months x 6 users will cost you 24 licenses. Then you have 1 license left, which you can use whenever you want.
So you always pay exactly $39 per user, per month!