diff --git a/core/secrets.py b/core/secrets.py
index 14f586c..f85fb08 100644
--- a/core/secrets.py
+++ b/core/secrets.py
@@ -45,7 +45,7 @@ def decode_jwt(
 ) -> dict[str, Any] | None:
     try:
         return jwt.decode(token, public_key, algo)
-    except jwt.ExpiredSignatureError:
+    except jwt.exceptions.PyJWTError:
         return
 
 
diff --git a/repositories/link_codes.py b/repositories/link_codes.py
index e59301e..78a4eba 100644
--- a/repositories/link_codes.py
+++ b/repositories/link_codes.py
@@ -32,3 +32,10 @@ async def get_link_code_by_code(session: AsyncSession, code: str) -> LinkCode |
     r = await session.execute(stmt)
 
     return r.scalar_one_or_none()
+
+
+async def use_link_code(session: AsyncSession, code: LinkCode) -> LinkCode:
+    code.status = LinkCodeStatus.USED
+    await session.commit()
+
+    return code
diff --git a/repositories/service_signatures.py b/repositories/service_signatures.py
index 04ad38e..2916e97 100644
--- a/repositories/service_signatures.py
+++ b/repositories/service_signatures.py
@@ -2,10 +2,15 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from db.models.service_signatures import ServiceSignature
+from schemas.enums import ServiceSignatureStatus
 
 
 async def get_active_signature_by_kid(session: AsyncSession, kid: str) -> ServiceSignature | None:
-    stmt = select(ServiceSignature).where(ServiceSignature.kid == kid)
+    stmt = (
+        select(ServiceSignature)
+        .where(ServiceSignature.kid == kid)
+        .where(ServiceSignature.status == ServiceSignatureStatus.ACTIVE)
+    )
     r = await session.execute(stmt)
 
     return r.scalar_one_or_none()
diff --git a/routes/link_codes.py b/routes/link_codes.py
index 21ea6ab..99f6fd9 100644
--- a/routes/link_codes.py
+++ b/routes/link_codes.py
@@ -7,7 +7,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from config import cfg
 from core.deps import get_auth_context, get_service_identity
 from db.session import get_db
-from repositories.link_codes import create_link_code, get_link_code_by_code
+from repositories.link_codes import create_link_code, get_link_code_by_code, use_link_code
 from repositories.users import UserRepository
 from schemas.dto import AuthContext
 from schemas.enums import LinkCodeStatus
@@ -41,6 +41,9 @@ async def consume_link_code(
     if not link_code:
         raise HTTPException(404, detail="Code not found")
 
+    if link_code.status != LinkCodeStatus.ACTIVE:
+        raise HTTPException(404, detail="Code expired or is invalid.")
+
     users_repo = UserRepository(session)
     user = await users_repo.get_user_by_id(link_code.user_id)
 
@@ -49,6 +52,8 @@ async def consume_link_code(
 
     user = await users_repo.update_telegram_id(user, payload.telegram_id)
 
+    await use_link_code(session, code=link_code)
+
     return UserInfo(
         username=user.username,
         telegram_id=user.telegram_id,
diff --git a/tests/test_link_code_routes.py b/tests/test_link_code_routes.py
index 537d873..525df3c 100644
--- a/tests/test_link_code_routes.py
+++ b/tests/test_link_code_routes.py
@@ -93,7 +93,7 @@ def test_consume_link_code_rejects_unknown_code(client):
 
 def test_consume_link_code_rejects_code_for_deleted_user(client):
     client.app.dependency_overrides[link_codes.get_service_identity] = service_identity
-    link_code = SimpleNamespace(user_id=42)
+    link_code = SimpleNamespace(user_id=42, status=LinkCodeStatus.ACTIVE)
     repository = SimpleNamespace(get_user_by_id=AsyncMock(return_value=None))
     with (
         patch("routes.link_codes.get_link_code_by_code", new=AsyncMock(return_value=link_code)),
@@ -110,7 +110,7 @@ def test_consume_link_code_rejects_code_for_deleted_user(client):
 
 def test_consume_link_code_updates_telegram_id_and_returns_user(client):
     client.app.dependency_overrides[link_codes.get_service_identity] = service_identity
-    link_code = SimpleNamespace(user_id=42)
+    link_code = SimpleNamespace(user_id=42, status=LinkCodeStatus.ACTIVE)
     user = SimpleNamespace(
         username="alice", telegram_id=12345, referal_code="ref-code", balance=100
     )