Start Date=01/01/2010 and End Date=31/12/201

DECLARE @subscriptionstartdate DATETIME,
        @subscriptionenddate DATETIME
SET @subscriptionstartdate = '20100101'
SET @subscriptionenddate = '20101231'
;WITH
  L0 AS (SELECT 1 AS C UNION ALL SELECT 1)    --2 rows
 ,L1 AS (SELECT 1 AS C FROM L0 AS A, L0 AS B)  --4 rows (2x2)
 ,L2 AS (SELECT 1 AS C FROM L1 AS A, L1 AS B)  --16 rows (4x4)
 ,L3 AS (SELECT 1 AS C FROM L2 AS A, L2 AS B)  --256 rows (16x16)
 --,L4 AS (SELECT 1 AS C FROM L3 AS A, L3 AS B)  --65536 rows (256x256)
 --,L5 AS (SELECT 1 AS C FROM L4 AS A, L4 AS B)  --4,294,967,296 rows (65536x65536)
 ,Nums AS (SELECT row_number() OVER (ORDER BY (SELECT 0)) -1 AS N FROM L2)
SELECT DATENAME(MONTH,DATEADD(MONTH,n,@subscriptionstartdate)) AS MnthName
FROM Nums
WHERE N<=256 AND DATEADD(DAY,DATEDIFF(DAY,0,DATEADD(MONTH,n,@subscriptionstartdate)),0) <= @subscriptionenddate
GO