diff --git a/packages/server/src/user/user.service.ts b/packages/server/src/user/user.service.ts
index 1b9a099..504e2f0 100644
--- a/packages/server/src/user/user.service.ts
+++ b/packages/server/src/user/user.service.ts
@@ -2,6 +2,8 @@ import { Injectable, NotFoundException } from '@nestjs/common'
 import { MembershipStatus, BookingStatus, UserRole, CardTypeCategory } from '@mp-pilates/shared'
 import type { PaginatedData, UserProfileResponse, UserStatsResponse } from '@mp-pilates/shared'
 import { PrismaService } from '../prisma/prisma.service'
+import { Membership, CardType, Prisma } from '@prisma/client'
+import { UpdateUserMembershipDto } from './dto/update-user-membership.dto'
 
 const VALID_CARD_TYPES = new Set<string>(Object.values(CardTypeCategory))
 
@@ -226,4 +228,68 @@ export class UserService {
 
     return { items, total, page, limit }
   }
+
+  // ─── Membership management ────────────────────────────────────────────────
+
+  async getUserMembership(userId: string) {
+    const membership = await this.prisma.membership.findFirst({
+      where: { userId },
+      include: { cardType: true },
+    })
+    return membership ? { ...membership, cardType: { ...membership.cardType } } : null
+  }
+
+  async updateUserMembership(userId: string, dto: UpdateUserMembershipDto) {
+    const now = new Date()
+    const expireDate = new Date(dto.expireDate)
+    const remainingTimes = dto.remainingTimes ?? null
+    const isTimeBased = remainingTimes !== null
+
+    let status: MembershipStatus = MembershipStatus.ACTIVE
+    if (expireDate < now) {
+      status = MembershipStatus.EXPIRED
+    } else if (isTimeBased && remainingTimes <= 0) {
+      status = MembershipStatus.USED_UP
+    }
+
+    const existing = await this.prisma.membership.findFirst({ where: { userId } })
+
+    let membership: Membership & { cardType: CardType }
+    if (existing) {
+      const updated = await this.prisma.membership.update({
+        where: { id: existing.id },
+        data: {
+          cardTypeId: dto.cardTypeId,
+          remainingTimes: dto.remainingTimes ?? null,
+          startDate: new Date(dto.startDate),
+          expireDate: new Date(dto.expireDate),
+          status,
+        },
+        include: { cardType: true },
+      })
+      membership = { ...updated, cardType: { ...updated.cardType } }
+    } else {
+      const created = await this.prisma.membership.create({
+        data: {
+          userId,
+          cardTypeId: dto.cardTypeId,
+          remainingTimes: dto.remainingTimes ?? null,
+          startDate: new Date(dto.startDate),
+          expireDate: new Date(dto.expireDate),
+          status,
+        },
+        include: { cardType: true },
+      })
+      membership = { ...created, cardType: { ...created.cardType } }
+    }
+
+    return membership
+  }
+
+  async deleteUserMembership(userId: string): Promise<void> {
+    await this.prisma.membership.updateMany({
+      where: { userId },
+      data: { status: MembershipStatus.EXPIRED },
+    })
+  }
 }