 Pop-Up Message Content - Your extra student limit has been exceeded kindly contact your School Administrator
Popup Condition 
1. On Valid Upto Date 
2. Upto date next update 
3. If Field is blank then - Show popup False 

Students Limit Setup Page - https://test.onlinevidyalaya.net/Pages/BaseFramework/Security/OrganizationSetup.aspx
Need a new Filed - Valid Upto

Alert Popup Required in Below mentioned pages :- (Popup Message Based on Valid Upto Date)
Search Button Click - https://test.onlinevidyalaya.net/Pages/StudentManagement/StudentSearch.aspx?MenuID=5210
Page Load - https://test.onlinevidyalaya.net/Pages/FeeManagement/FeeReceipt.aspx