diff --git a/internal/application/purchase/dto.go b/internal/application/purchase/dto.go
index 1dab50a..0834427 100644
--- a/internal/application/purchase/dto.go
+++ b/internal/application/purchase/dto.go
@@ -10,10 +10,15 @@ type PurchaseDTO struct {
 	ContentType purchase.ContentType `json:"contentType"`
 	Price       float64              `json:"price"`
 	Status      int8                 `json:"status"`
+	Duration    int                  `json:"duration"` // 购买时长（月），文章为0表示永久
 	CreatedAt   string               `json:"createdAt"`
 	UpdatedAt   string               `json:"updatedAt"`
 }
 
+/*
+	过期时间计算出来
+*/
+
 // ToDTO 转换为DTO
 func ToDTO(p *purchase.Purchase) *PurchaseDTO {
 	if p == nil {