Entity Framework Object Context in ASP.NET Session object?

We have a multi-layered Asp.NET Web Forms application. The data layer has a class called DataAccess which impements IDisposable and has an instance of our Entity Framework Object Context as a private field. The class has a number of public methods returning various collections of Entities and will dispose its Object Context when it is disposed.

Managing Entity Framework ObjectContext in ASP.NET

I’m using the Entity Framework for an ASP.NET Web Forms application and I’m wondering how I should deal with ObjectContext and it’s lifetime.
For example, I have an InviteService class that manages invites such as creating and accepting invites. The class itself is in another project/namespace from the Web project.
An InviteUsers() method creates Invite entities for a list of users, calls a repository to save them to the database and mails each user an invite link.