Process Priority Optimizer is a shareware program. If you use this program regularly you should register to award the author's many years work and support continuous development.
With registration you will receive a personalized code in e-mail, that you can use to register the program.
Registration of any of the following licenses means unlimited free updates and you just need to obtain the newest version only.
If you are a home user or want to register for a company to run on a single computer this is the registration for you. For home use this registration allows using Process Priority Optimizer on as many home computers as you wish.