I bought a card. The Unicom business hall on my mobile phone shows the king card, and there is a package with 40g national traffic for 20 yuan. Forever. Why?

As the information you provided is incomplete, the fee for Tencent King Card is as follows:

1, monthly rent 19 yuan, including caller ID;

2. Domestic voice call 0. 1 yuan/minute; Domestic calls are free, and other international services are charged at standard rates;

3. Enjoy exclusive application traffic for free in Chinese mainland (except Hong Kong, Macao and Taiwan); The domestic flow within the non-flow range is 0. 1 yuan /MB, and 0. 1 yuan /MB will be deducted when it reaches 10MB; if it is less than 1MB, it will be charged as 1MB; After reaching 10MB (1 yuan), the daily rental service will be started automatically (valid on the same day, and automatically renewed every day), and you can use 800M for free at most (the daily rental upgrade activity will be charged according to the upgrade fee); By default, the service of traffic capping is provided: after you turn on the "automatic traffic unsealing service", all traffic exceeding 40GB (including directional traffic such as Tencent's exclusive traffic) will be calculated according to other general traffic packages you ordered before. If there are no other traffic package products, charge according to your daily rental package for that month; However, according to the rules of directed traffic packets, directed traffic packets cannot be used;

4. Domestic SMS/MMS 0. 1 RMB/piece.