Welcome to CardsChat Lupus,
All
poker sites have different rules and terms of service, and not all of them allow the use of HUDs. So, whatever
poker site you might be using, please make sure first (by reading their rules, or by asking from them) that you are allowed to use a HUD.
Using a HUD on a site that forbids it might result in terminating your account. Make no mistake - they will find out if you do.
The PT4 license has no end date. It means that as long as updates for PT4 are built you will receive them. Somewhere down the road there will be a time when PT5 rolls out. At that moment you will probably still receive updates for PT4, but your license will not allow you to upgrade to PT5 without a new license. But you'll cross that bridge when you come to it.
In the future if you have support questions for PT4 it is better to ask them in this thread:
https://www.cardschat.com/forum/poker-software-tools-61/official-pokertracker-support-thread-216564/