diff --git a/auth/rule.go b/auth/rule.go
index bb00b9d..f4416a1 100644
--- a/auth/rule.go
+++ b/auth/rule.go
@@ -9,15 +9,21 @@ import (
 
 const (
 	ErrNotAuthenticated = "not authenticated error (model: %s)"
-	ErrNotSetPrice      = "the price of the model is not set error (model: %s)"
+	ErrNotSetPrice      = "the price of the model is not set (model: %s)"
 	ErrNotEnoughQuota   = "user quota is not enough error (model: %s, minimum quota: %0.2f, your quota: %0.2f)"
 )
 
 // CanEnableModel returns whether the model can be enabled (without subscription)
 func CanEnableModel(db *sql.DB, user *User, model string) error {
 	isAuth := user != nil
+	isAdmin := isAuth && user.IsAdmin(db)
+
 	charge := channel.ChargeInstance.GetCharge(model)
 
+	if charge.IsUnsetType() && !isAdmin {
+		return fmt.Errorf(ErrNotSetPrice, model)
+	}
+
 	if !charge.IsBilling() {
 		// return if is the user is authenticated or anonymous is allowed for this model
 		if charge.SupportAnonymous() || isAuth {
@@ -33,9 +39,6 @@ func CanEnableModel(db *sql.DB, user *User, model string) error {
 
 	// return if the user is authenticated and has enough quota
 	limit := charge.GetLimit()
-	if limit == -1 {
-		return fmt.Errorf(ErrNotSetPrice, model)
-	}
 
 	quota := user.GetQuota(db)
 	if quota < limit {
diff --git a/channel/charge.go b/channel/charge.go
index 460d807..710c168 100644
--- a/channel/charge.go
+++ b/channel/charge.go
@@ -74,6 +74,7 @@ func (m *ChargeManager) GetCharge(model string) *Charge {
 	return &Charge{
 		Type:      globals.NonBilling,
 		Anonymous: false,
+		Unset:     true,
 	}
 }
 
@@ -236,6 +237,10 @@ func (m *ChargeManager) GetRuleByModel(model string) *Charge {
 	return nil
 }
 
+func (c *Charge) IsUnsetType() bool {
+	return c.Unset
+}
+
 func (c *Charge) GetType() string {
 	if c.Type == "" {
 		return globals.NonBilling
@@ -283,7 +288,7 @@ func (c *Charge) GetLimit() float32 {
 		// 1k input tokens + 1k output tokens
 		return c.GetInput() + c.GetOutput()
 	default:
-		return -1
+		return 0
 	}
 }
 
diff --git a/channel/types.go b/channel/types.go
index 4d36c66..d800663 100644
--- a/channel/types.go
+++ b/channel/types.go
@@ -39,6 +39,7 @@ type Charge struct {
 	Input     float32  `json:"input" mapstructure:"input"`
 	Output    float32  `json:"output" mapstructure:"output"`
 	Anonymous bool     `json:"anonymous" mapstructure:"anonymous"`
+	Unset     bool     `json:"-" mapstructure:"-"`
 }
 
 type ChargeSequence []*Charge