diff --git a/aleph_message/models/execution/environment.py b/aleph_message/models/execution/environment.py
index e0eae1d..9e3b0e6 100644
--- a/aleph_message/models/execution/environment.py
+++ b/aleph_message/models/execution/environment.py
@@ -165,6 +165,9 @@ class NodeRequirements(HashableModel):
     node_hash: Optional[ItemHash] = Field(
         default=None, description="Hash of the compute resource node that must be used"
     )
+    terms_and_conditions: Optional[ItemHash] = Field(
+        default=None, description="Terms and conditions of this CRN"
+    )
 
     class Config:
         extra = Extra.forbid
diff --git a/aleph_message/models/execution/instance.py b/aleph_message/models/execution/instance.py
index ebb8d48..7175f5d 100644
--- a/aleph_message/models/execution/instance.py
+++ b/aleph_message/models/execution/instance.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from pydantic import Field
+from pydantic import Field, validator
 
 from aleph_message.models.abstract import HashableModel
 
@@ -32,3 +32,20 @@ class InstanceContent(BaseExecutableContent):
     rootfs: RootfsVolume = Field(
         description="Root filesystem of the system, will be booted by the kernel"
     )
+
+    @validator("requirements")
+    def terms_and_conditions_only_for_payg_instances(cls, v, values, field, config):
+        if not v.node or not v.node.terms_and_conditions:
+            return v
+
+        if not values["payment"].is_stream:
+            raise ValueError(
+                f"only PAYG/stream instance can have a terms_and_conditions, not '{values['payment'].type}' instances"
+            )
+
+        if not v.node.node_hash:
+            raise ValueError(
+                "an instance with a terms_and_conditions needs a requirements.node.node_hash value"
+            )
+
+        return v
diff --git a/aleph_message/tests/messages/instance_content.json b/aleph_message/tests/messages/instance_content.json
new file mode 100644
index 0000000..8170b7e
--- /dev/null
+++ b/aleph_message/tests/messages/instance_content.json
@@ -0,0 +1,69 @@
+{
+    "sender": "0x3E1aba4ad853Dd7Aa531aB59F10bd9f4d89aebaF",
+    "chain": "ETH",
+    "signature": "0x5ff79fb62190455b485e6a891d7bbee3a992ca8d0361bbd55f12a18176d9f668692601a75c3344cb880a479fc5920efc53036450bce8e891e13b9aa5618b2aba1b",
+    "type": "INSTANCE",
+    "item_content": "{\"address\":\"0x3E1aba4ad853Dd7Aa531aB59F10bd9f4d89aebaF\",\"time\":1732118563.2142403,\"allow_amend\":false,\"metadata\":{\"name\":\"test-payg-base\"},\"authorized_keys\":[\"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDQVOxf7uOhIlt7GbPD1XnnSGPvj4t9cdjzB2AYRt3jlPT5w9gcUr2WYj+EPYDXig+imDYELtZNx6Pvg5jruKjFaAtugV3ta0NHPamGNIVPxSNdwx+teLIEs/A9FPT3jeohvU+JpjrKLjBtsfyVJ9iBf/Iswm2rcc/33k4LumwFgkpgNswIc4Da6L1K7EHrlkSbdtdBMdlxLGaU2eFp140JwOTCBBF4rL0JNzPDCzLdkKsj2hQOWg6IIwhQzg3B6o1lY2xoGrVWL4+s+TKSgv1VQY0I1Fmyw+33bWYw/sZlhEpflFYp565Nh2+n3nbYNvmouH4RTLwNUF4z2vvG3J3HVlkd5Q0SCNvPk6FAkAgZ2oXK2P79enlglL+NcFr21QInbacclAtESpPop3dSdLNbR8NvQwh53eELcBPtGFQLRPP9ZfOwtG1hZhVinCeb6fpgcOsBXn0Xo11DQ3XNgfMho632FPqujQtggkyZt/2a53oGEbrrfGgDhiLCGswUM1k= root@rpi\"],\"environment\":{\"internet\":true,\"aleph_api\":true,\"hypervisor\":\"qemu\",\"reproducible\":false,\"shared_cache\":false},\"resources\":{\"vcpus\":1,\"memory\":2048,\"seconds\":30},\"payment\":{\"chain\":\"BASE\",\"receiver\":\"0xFeF2b33478f906eDE5ee96110b2342861cF1569A\",\"type\":\"superfluid\"},\"requirements\":{\"node\":{\"node_hash\":\"2cdb78cf561c6f0f839edb817395d3b5ece20d89125c5afba658f9170d6932c8\"}},\"volumes\":[],\"rootfs\":{\"parent\":{\"ref\":\"b6ff5c3a8205d1ca4c7c3369300eeafff498b558f71b851aa2114afd0a532717\",\"use_latest\":true},\"persistence\":\"host\",\"size_mib\":10240}}",
+    "item_type": "inline",
+    "item_hash": "b28fa9a9ede14c9bbd6fde8959be07cfd25a3358d08e01405301adc5a1a2b2c8",
+    "time": "2024-11-20T16:02:43.214390+00:00",
+    "channel": "ALEPH-CLOUDSOLUTIONS",
+    "content": {
+        "address": "0x3E1aba4ad853Dd7Aa531aB59F10bd9f4d89aebaF",
+        "time": 1732118563.2142403,
+        "allow_amend": false,
+        "metadata": {
+            "name": "test-payg-base"
+        },
+        "authorized_keys": [
+            "ssh-rsa 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 root@rpi"
+        ],
+        "variables": null,
+        "environment": {
+            "internet": true,
+            "aleph_api": true,
+            "hypervisor": "qemu",
+            "trusted_execution": null,
+            "reproducible": false,
+            "shared_cache": false
+        },
+        "resources": {
+            "vcpus": 1,
+            "memory": 2048,
+            "seconds": 30,
+            "published_ports": null
+        },
+        "payment": {
+            "chain": "BASE",
+            "receiver": "0xFeF2b33478f906eDE5ee96110b2342861cF1569A",
+            "type": "superfluid"
+        },
+        "requirements": {
+            "cpu": null,
+            "node": {
+                "owner": null,
+                "address_regex": null,
+                "node_hash": "2cdb78cf561c6f0f839edb817395d3b5ece20d89125c5afba658f9170d6932c8",
+                "terms_and_conditions": "2cdb78cf561c6f0f839edb817395d3b5ece20d89125c5afba658f9170d6932c8"
+            }
+        },
+        "volumes": [],
+        "replaces": null,
+        "rootfs": {
+            "parent": {
+                "ref": "b6ff5c3a8205d1ca4c7c3369300eeafff498b558f71b851aa2114afd0a532717",
+                "use_latest": true
+            },
+            "persistence": "host",
+            "size_mib": 10240
+        }
+    },
+    "confirmed": true,
+    "confirmations": [
+        {
+            "chain": "ETH",
+            "height": 21230293,
+            "hash": "0x8bd25e2384dbb2da8c516880c47148304ed9ee1b7dfff8a327f8ccfa97ea29f4"
+        }
+    ]
+}
diff --git a/aleph_message/tests/test_models.py b/aleph_message/tests/test_models.py
index 78cdf04..c642db1 100644
--- a/aleph_message/tests/test_models.py
+++ b/aleph_message/tests/test_models.py
@@ -14,6 +14,7 @@
     AggregateMessage,
     ForgetMessage,
     InstanceMessage,
+    InstanceContent,
     ItemType,
     MessagesResponse,
     MessageType,
@@ -349,3 +350,35 @@ def test_messages_from_disk():
                 console.print(message_dict)
                 console.print_json(e.json())
                 raise
+
+
+def test_terms_and_conditions_only_for_payg_instances():
+    """Ensure that only instance with PAYG and a node_hash can have a terms_and_conditions"""
+    path = os.path.abspath(os.path.join(__file__, "../messages/instance_content.json"))
+    with open(path) as fd:
+        message_dict = json.load(fd)
+
+    # this one is valid
+    instance_message = create_message_from_json(
+        json.dumps(message_dict), factory=InstanceMessage
+    )
+
+    assert isinstance(instance_message.content, InstanceContent)
+    assert instance_message.content.payment and instance_message.content.payment.is_stream
+
+    message_dict["content"]["payment"]["type"] = "hold"
+
+    # can't have a terms_and_conditions with hold
+    with pytest.raises(ValueError):
+        instance_message = create_message_from_json(
+            json.dumps(message_dict), factory=InstanceMessage
+        )
+
+    message_dict["content"]["payment"]["type"] = "superfluid"
+
+    # a node_hash is needed for a terms_and_conditions
+    del message_dict["content"]["requirements"]["node"]["node_hash"]
+    with pytest.raises(ValueError):
+        instance_message = create_message_from_json(
+            json.dumps(message_dict), factory=InstanceMessage
+        )