diff --git a/commands/discommand.go b/commands/discommand.go
index fe30ed4..b550888 100644
--- a/commands/discommand.go
+++ b/commands/discommand.go
@@ -4,6 +4,7 @@ import (
 	"sync"
 
 	"git.wh64.net/muffin/goMuffin/configs"
+	"git.wh64.net/muffin/goMuffin/databases"
 	"git.wh64.net/muffin/goMuffin/utils"
 	"github.com/bwmarrin/discordgo"
 )
@@ -17,6 +18,7 @@ type modalParse func(ctx *ModalContext) bool
 type componentParse func(ctx *ComponentContext) bool
 
 type Category string
+type CommandFlags uint8
 
 type DetailedDescription struct {
 	Usage    string
@@ -30,6 +32,7 @@ type Command struct {
 	Category                   Category
 	RegisterApplicationCommand bool
 	RegisterMessageCommand     bool
+	Flags                      CommandFlags
 	MessageRun                 messageRun
 	ChatInputRun               chatInputRun
 }
@@ -78,6 +81,11 @@ const (
 	DeveloperOnly Category = "개발자 전용"
 )
 
+const (
+	CommandFlagsIsDeveloper CommandFlags = 1 << iota
+	CommandFlagsIsRegistered
+)
+
 var (
 	commandMutex   sync.Mutex
 	componentMutex sync.Mutex
@@ -118,10 +126,15 @@ func (d *DiscommandStruct) LoadModal(m *Modal) {
 	d.Modals = append(d.Modals, m)
 }
 
-func (d *DiscommandStruct) MessageRun(name string, s *discordgo.Session, m *discordgo.MessageCreate, args []string) {
-	if command, ok := d.Commands[name]; ok {
-		if command.Category == DeveloperOnly && m.Author.ID != configs.Config.Bot.OwnerId {
-			utils.NewMessageSender(&utils.MessageCreate{MessageCreate: m, Session: s}).
+func (d *DiscommandStruct) MessageRun(name string, s *discordgo.Session, msg *discordgo.MessageCreate, args []string) {
+	m := &utils.MessageCreate{
+		MessageCreate: msg,
+		Session:       s,
+	}
+
+	if command, ok := d.Commands[name]; ok && command.RegisterMessageCommand {
+		if command.Flags&CommandFlagsIsDeveloper != 0 && m.Author.ID != configs.Config.Bot.OwnerId {
+			utils.NewMessageSender(m).
 				AddComponents(utils.GetErrorContainer(discordgo.TextDisplay{Content: "해당 명령어는 개발자만 사용 가능해요."})).
 				SetComponentsV2(true).
 				SetReply(true).
@@ -129,24 +142,48 @@ func (d *DiscommandStruct) MessageRun(name string, s *discordgo.Session, m *disc
 			return
 		}
 
-		if !command.RegisterMessageCommand {
+		if command.Flags&CommandFlagsIsRegistered != 0 && !databases.Database.IsUser(m.Author.ID) {
+			utils.NewMessageSender(m).
+				AddComponents(utils.GetUserIsNotRegisteredErrContainer(configs.Config.Bot.Prefix)).
+				SetComponentsV2(true).
+				SetReply(true).
+				Send()
 			return
 		}
 
-		command.MessageRun(&MsgContext{&utils.MessageCreate{
-			MessageCreate: m,
-			Session:       s,
-		}, &args, command})
+		command.MessageRun(&MsgContext{m, &args, command})
 	}
 }
 
-func (d *DiscommandStruct) ChatInputRun(name string, s *discordgo.Session, i *discordgo.InteractionCreate) {
+func (d *DiscommandStruct) ChatInputRun(name string, s *discordgo.Session, inter *discordgo.InteractionCreate) {
+	i := &utils.InteractionCreate{
+		InteractionCreate: inter,
+		Session:           s,
+		Options:           utils.GetInteractionOptions(inter),
+	}
+
+	i.InteractionCreate.User = utils.GetInteractionUser(inter)
+
 	if command, ok := d.Commands[name]; ok && command.RegisterApplicationCommand {
-		command.ChatInputRun(&ChatInputContext{&utils.InteractionCreate{
-			InteractionCreate: i,
-			Session:           s,
-			Options:           utils.GetInteractionOptions(i),
-		}, command})
+		if command.Flags&CommandFlagsIsDeveloper != 0 && i.User.ID != configs.Config.Bot.OwnerId {
+			utils.NewMessageSender(i).
+				AddComponents(utils.GetErrorContainer(discordgo.TextDisplay{Content: "해당 명령어는 개발자만 사용 가능해요."})).
+				SetComponentsV2(true).
+				SetReply(true).
+				Send()
+			return
+		}
+
+		if command.Flags&CommandFlagsIsRegistered != 0 && !databases.Database.IsUser(i.User.ID) {
+			utils.NewMessageSender(i).
+				AddComponents(utils.GetUserIsNotRegisteredErrContainer(configs.Config.Bot.Prefix)).
+				SetComponentsV2(true).
+				SetReply(true).
+				Send()
+			return
+		}
+
+		command.ChatInputRun(&ChatInputContext{i, command})
 	}
 }
 
diff --git a/commands/reloadPrompt.go b/commands/reloadPrompt.go
index 3c4a033..0681b95 100644
--- a/commands/reloadPrompt.go
+++ b/commands/reloadPrompt.go
@@ -21,6 +21,7 @@ var ReloadPromptCommand *Command = &Command{
 	Category:                   DeveloperOnly,
 	RegisterApplicationCommand: false,
 	RegisterMessageCommand:     true,
+	Flags:                      CommandFlagsIsDeveloper,
 	MessageRun: func(ctx *MsgContext) {
 		err := chatbot.ChatBot.ReloadPrompt()
 		if err != nil {
diff --git a/commands/switchMode.go b/commands/switchMode.go
index 673668e..4888b56 100644
--- a/commands/switchMode.go
+++ b/commands/switchMode.go
@@ -20,6 +20,7 @@ var SwitchModeCommand *Command = &Command{
 	Category:                   DeveloperOnly,
 	RegisterApplicationCommand: false,
 	RegisterMessageCommand:     true,
+	Flags:                      CommandFlagsIsDeveloper,
 	MessageRun: func(ctx *MsgContext) {
 		chatbot.ChatBot.SwitchMode()
 
diff --git a/databases/User.go b/databases/User.go
new file mode 100644
index 0000000..101dee9
--- /dev/null
+++ b/databases/User.go
@@ -0,0 +1,29 @@
+package databases
+
+import (
+	"context"
+	"time"
+
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+type InsertUser struct {
+	UserId    string    `bson:"user_id"`
+	CreatedAt time.Time `bson:"created_at"`
+}
+
+type User struct {
+	Id        bson.ObjectID `bson:"_id"`
+	UserId    string        `bson:"user_id"`
+	CreatedAt time.Time     `bson:"created_at"`
+}
+
+func (d *MuffinDatabase) IsUser(userId string) bool {
+	var user *User
+	d.Users.FindOne(context.TODO(), bson.D{{Key: "user_id", Value: userId}}).Decode(&user)
+
+	if user != nil {
+		return true
+	}
+	return false
+}
diff --git a/databases/database.go b/databases/database.go
index 75a9cf8..fe7da03 100644
--- a/databases/database.go
+++ b/databases/database.go
@@ -13,6 +13,7 @@ type MuffinDatabase struct {
 	Learns *mongo.Collection
 	Texts  *mongo.Collection
 	Memory *mongo.Collection
+	Users  *mongo.Collection
 }
 
 var Database *MuffinDatabase
@@ -36,5 +37,6 @@ func Connect() (*MuffinDatabase, error) {
 		Learns: client.Database(configs.Config.Database.Name).Collection("learn"),
 		Texts:  client.Database(configs.Config.Database.Name).Collection("text"),
 		Memory: client.Database(configs.Config.Database.Name).Collection("memory"),
+		Users:  client.Database(configs.Config.Database.Name).Collection("user"),
 	}, nil
 }
diff --git a/utils/embed.go b/utils/embed.go
index 4093445..861d260 100644
--- a/utils/embed.go
+++ b/utils/embed.go
@@ -1,6 +1,10 @@
 package utils
 
-import "github.com/bwmarrin/discordgo"
+import (
+	"fmt"
+
+	"github.com/bwmarrin/discordgo"
+)
 
 const (
 	EmbedDefault int = 0xaddb87
@@ -33,3 +37,9 @@ func GetSuccessContainer(components ...discordgo.MessageComponent) *discordgo.Co
 	c.Components = append(c.Components, components...)
 	return c
 }
+
+func GetUserIsNotRegisteredErrContainer(prefix string) *discordgo.Container {
+	return GetErrorContainer(discordgo.TextDisplay{
+		Content: fmt.Sprintf("해당 기능은 등록된 사용자만 쓸 수 있어요. `%s가입`으로 가입해주새요.", prefix),
+	})
+}
diff --git a/utils/interactions.go b/utils/interactions.go
index 0cc4461..3f0dda7 100644
--- a/utils/interactions.go
+++ b/utils/interactions.go
@@ -53,6 +53,17 @@ func GetInteractionOptions(i *discordgo.InteractionCreate) map[string]*discordgo
 	return optsMap
 }
 
+func GetInteractionUser(i *discordgo.InteractionCreate) *discordgo.User {
+	if i.Member != nil {
+		return i.Member.User
+	}
+
+	if i.User != nil {
+		return i.User
+	}
+	return nil
+}
+
 // DeferReply to this interaction.
 func (i *InteractionCreate) DeferReply(data *discordgo.InteractionResponseData) error {
 	err := i.Session.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
diff --git a/utils/messageBuilder.go b/utils/messageBuilder.go
index 612a1ce..bd92070 100644
--- a/utils/messageBuilder.go
+++ b/utils/messageBuilder.go
@@ -63,7 +63,7 @@ func (s *MessageSender) Send() error {
 	var flags discordgo.MessageFlags
 
 	if s.ComponentsV2 {
-		flags = flags | discordgo.MessageFlagsIsComponentsV2
+		flags |= discordgo.MessageFlagsIsComponentsV2
 	}
 
 	switch m := s.m.(type) {
@@ -85,7 +85,7 @@ func (s *MessageSender) Send() error {
 		return err
 	case *InteractionCreate:
 		if s.Ephemeral {
-			flags = flags | discordgo.MessageFlagsEphemeral
+			flags |= discordgo.MessageFlagsEphemeral
 		}
 
 		if m.Replied || m.Deferred {