diff --git a/session/common.go b/session/common.go
index 25d05f2..957f44f 100644
--- a/session/common.go
+++ b/session/common.go
@@ -17,9 +17,10 @@ type Authorization struct {
 	invalidated string
 
 	// by authorization provider
-	Platform string `bson:"p" json:"p"`
-	Uid      string `bson:"u" json:"u"`
-	Alias    string `bson:"al" json:"al"`
+	Platform    string             `bson:"p" json:"p"`
+	Uid         string             `bson:"u" json:"u"`
+	Alias       string             `bson:"al" json:"al"`
+	CreatedTime primitive.DateTime `bson:"ct" json:"ct"`
 }
 
 func (auth *Authorization) ToStrings() []string {