Study.com referral code - how long?

[Mab81]

Hi everyone, i got a referral code from a member here for 20 percent off. The email did not say it was only 20 percent off the 1st month, but this seems to be the case. When I look in my billing, it shows I was billed at the discounted rate for november; but it shows that i will be billed the full $199 for the next month. is this normal? I thought since it didn't say one month only, that it would be every month.