diff --git a/main.py b/main.py
index 6a99495..6a9f9a3 100644
--- a/main.py
+++ b/main.py
@@ -1,6 +1,7 @@
 from fastapi import FastAPI, HTTPException
 from db import MySQLDB
 from PlayerSubscription import PlayerSubscription
+from utils import get_unix_timestamp_after_days
 
 app = FastAPI()
 db = MySQLDB()
@@ -16,11 +17,18 @@ async def subscribe(player_data: PlayerSubscription):
             raise HTTPException(status_code=404, detail="Player not found")
         uuid = result[0][0]
 
+        if player_data.expiry is not None:
+            if player_data.expiry < 0:
+                raise HTTPException(status_code=400, detail="Expiry must be a positive integer")
+            expiry_timestamp = get_unix_timestamp_after_days(player_data.expiry)
+        else:
+            raise HTTPException(status_code=400, detail="Expiry must be a positive integer")
+
         subscription_query = """
             INSERT INTO luckperms_user_permissions (uuid, permission, value, server, world, expiry, contexts)
             VALUES (%s, %s, %s, %s, %s, %s, %s)
         """
-        await db.execute(subscription_query, uuid, 'group.subscribe', 1, 'global', 'global', player_data.expiry, "{}")
+        await db.execute(subscription_query, uuid, 'group.subscribe', 1, 'global', 'global', expiry_timestamp, "{}")
     finally:
         await db.close()
 
diff --git a/utils.py b/utils.py
index 87f7530..bbc0444 100644
--- a/utils.py
+++ b/utils.py
@@ -1,11 +1,12 @@
 import yaml
+import datetime
 
 def read_config(config_file):
     with open(config_file, 'r') as file:
         config = yaml.safe_load(file)
     return config
 
-def get_parameters():
+def get_parameters() -> dict:
     parameters = {}
     config = read_config('config.yml')
     for key, value in config.items():
@@ -15,3 +16,10 @@ def get_parameters():
         else:
             parameters[key] = value
     return parameters
+
+def get_unix_timestamp_after_days(days: int) -> int:
+    return int((datetime.datetime.now() + datetime.timedelta(days=days)).timestamp()) if days != 0 else 0
+
+def get_uts(timestamp: int) -> int:
+    return datetime.datetime.utcfromtimestamp(timestamp)
+