No monthly fee. No hidden cost. Only SMS cost. Credits and Account won't expire after purchased
Input your email for the credits then click "Check email" first and it will take you to pay via Paypal if email is existed. Register if you do not have an account.

Price of credits 
130 credits 275 credits 430 credits 1050 credits 2200 credits 5,300 credits 10,500 credits 15,000 credits 20,000 credits 50,000 credits 50,000+ credits
USD10.00 USD20.00 USD30.00 USD70.00 USD140 USD325 USD600 USD825 USD1,000 USD2,250 Contact Sales

 Check credits per SMS to your mobile phone        Local mobile number      

Or you can Purchase license for CPU_Alert / Port_Alert email alerts only version, no registration required for SMS alerts