Once you purchased the R6S Script you will have it forever. After 3 months it is required to have the active subscription to be able to use the R6S Script.
If you for example use it for 3 months and then come back after half a year, you still have the R6S Script but need to purchase the active subscription.
The active subscription introduced some changes such as:
Heavily modifed custom builds (signature) for each customer
New Bypass
Free HWID resets
Automated weapon recognition (which is currently in update for R6S)