diff --git a/src/api2/node/subscription.rs b/src/api2/node/subscription.rs
index 3ce7ce98..309d0960 100644
--- a/src/api2/node/subscription.rs
+++ b/src/api2/node/subscription.rs
@@ -7,7 +7,7 @@ use crate::tools;
 use crate::tools::subscription::{self, SubscriptionStatus, SubscriptionInfo};
 use crate::config::acl::{PRIV_SYS_AUDIT,PRIV_SYS_MODIFY};
 use crate::config::cached_user_info::CachedUserInfo;
-use crate::api2::types::{NODE_SCHEMA, Authid};
+use crate::api2::types::{NODE_SCHEMA, SUBSCRIPTION_KEY_SCHEMA, Authid};
 
 #[api(
     input: {
@@ -124,9 +124,7 @@ fn get_subscription(
                 schema: NODE_SCHEMA,
             },
             key: {
-                description: "Proxmox Backup Server subscription key",
-                type: String,
-                max_length: 32,
+                schema: SUBSCRIPTION_KEY_SCHEMA,
             },
         },
     },
diff --git a/src/api2/types/mod.rs b/src/api2/types/mod.rs
index bfa46382..f67d48ed 100644
--- a/src/api2/types/mod.rs
+++ b/src/api2/types/mod.rs
@@ -73,6 +73,8 @@ const_regex!{
 
     pub ACL_PATH_REGEX = concat!(r"^(?:/|", r"(?:/", PROXMOX_SAFE_ID_REGEX_STR!(), ")+", r")$");
 
+    pub SUBSCRIPTION_KEY_REGEX = concat!(r"^pbs(?:[cbsp])-[0-9a-f]{10}$");
+
     pub BLOCKDEVICE_NAME_REGEX = r"^(:?(:?h|s|x?v)d[a-z]+)|(:?nvme\d+n\d+)$";
 
     pub ZPOOL_NAME_REGEX = r"^[a-zA-Z][a-z0-9A-Z\-_.:]+$";
@@ -129,6 +131,9 @@ pub const CIDR_V6_FORMAT: ApiStringFormat =
 pub const CIDR_FORMAT: ApiStringFormat =
     ApiStringFormat::Pattern(&CIDR_REGEX);
 
+pub const SUBSCRIPTION_KEY_FORMAT: ApiStringFormat =
+    ApiStringFormat::Pattern(&SUBSCRIPTION_KEY_REGEX);
+
 pub const BLOCKDEVICE_NAME_FORMAT: ApiStringFormat =
     ApiStringFormat::Pattern(&BLOCKDEVICE_NAME_REGEX);
 
@@ -348,6 +353,12 @@ pub const DNS_NAME_OR_IP_SCHEMA: Schema = StringSchema::new("DNS name or IP addr
     .format(&DNS_NAME_OR_IP_FORMAT)
     .schema();
 
+pub const SUBSCRIPTION_KEY_SCHEMA: Schema = StringSchema::new("Proxmox Backup Server subscription key.")
+    .format(&SUBSCRIPTION_KEY_FORMAT)
+    .min_length(15)
+    .max_length(16)
+    .schema();
+
 pub const BLOCKDEVICE_NAME_SCHEMA: Schema = StringSchema::new("Block device name (/sys/block/<name>).")
     .format(&BLOCKDEVICE_NAME_FORMAT)
     .min_length(3)