diff --git a/models/booking/booking.go b/models/booking/booking.go
index 64622e1..35ce927 100644
--- a/models/booking/booking.go
+++ b/models/booking/booking.go
@@ -34,6 +34,8 @@ type Booking struct {
 
 	ResourceType tools.DataType `json:"resource_type,omitempty" bson:"resource_type,omitempty" validate:"required"` // ResourceType is the type of the resource
 	ResourceID   string         `json:"resource_id,omitempty" bson:"resource_id,omitempty" validate:"required"`     // could be a Compute or a Storage
+	InstanceID   string         `json:"instance_id,omitempty" bson:"instance_id,omitempty" validate:"required"`     // could be a Compute or a Storage
+
 }
 
 func (b *Booking) CalcDeltaOfExecution() map[string]map[string]models.MetricResume {
diff --git a/models/resources/purchase_resource/purchase_resource.go b/models/resources/purchase_resource/purchase_resource.go
index d4c437e..ec416a5 100644
--- a/models/resources/purchase_resource/purchase_resource.go
+++ b/models/resources/purchase_resource/purchase_resource.go
@@ -9,12 +9,14 @@ import (
 
 type PurchaseResource struct {
 	utils.AbstractObject
-	DestPeerID   string				 	`json:"dest_peer_id" bson:"dest_peer_id"`
+	DestPeerID   string                 `json:"dest_peer_id" bson:"dest_peer_id"`
 	PricedItem   map[string]interface{} `json:"priced_item,omitempty" bson:"priced_item,omitempty" validate:"required"`
 	ExecutionsID string                 `json:"executions_id,omitempty" bson:"executions_id,omitempty" validate:"required"` // ExecutionsID is the ID of the executions
 	EndDate      *time.Time             `json:"end_buying_date,omitempty" bson:"end_buying_date,omitempty"`
 	ResourceID   string                 `json:"resource_id" bson:"resource_id" validate:"required"`
-	ResourceType tools.DataType         `json:"resource_type" bson:"resource_type" validate:"required"`
+	InstanceID   string                 `json:"instance_id,omitempty" bson:"instance_id,omitempty" validate:"required"` // could be a Compute or a Storage
+
+	ResourceType tools.DataType `json:"resource_type" bson:"resource_type" validate:"required"`
 }
 
 func (d *PurchaseResource) GetAccessor(request *tools.APIRequest) utils.Accessor {