What other attribute should i add for my Gorm table?

Question

My goal is to simply join three tables (Sorry my knowledge in sql is limited)

I'm building a community-based platform like Patreon where each community can have different plans (Free, Paid)

Example Code:

type User struct {
    Communities []Community `gorm:"many2many:user_communities" json:"communities"`
}

type Community struct {
    UserID `json:"userID"`
    Users []User `gorm:"many2many:user_communities" json:"users"`
    Plans []Plan `json:"plans"`
    // How do i add another attirbute to check for user with different plan?
}

type Plan struct {
    CommunityID uint `json:"communityID"`
    Name string `json:"name"`
    Price string `json:"price"`
}

Based on the model above

1. One user can join many communities
2. One community can have many users
3. One user can own a community (creator)
4. and for each community, one user can join for the different plans (Free, Paid)

I'm more focused on how to solve number 4

So the question here is what should I add for my community table to differentiate between the user who joins as Free plan or Paid plan?

because I can only query users who belong to a specific community not users who belong to that community based on a Free or Paid plan.

Example query

// Find whether that user belongs to a community
if err := database.Mysql.Table("users u").Joins("JOIN user_communities uc ON u.id = uc.user_id").Where("u.id = ? AND uc.community_id = ?", userID, communityID).Select("1").Scan(&found).Error; err != nil {
    c.JSON(http.StatusBadRequest, gin.H{"error": "error happened"})
    return
}