MIT has a subscription to Zotero which provides MIT affiliates with unlimited storage. The unlimited storage will be automatically applied if you have a mit.edu email address affiliated with your account.
To add an email address, login to your Zotero account and add an email address under "Manage Email Addresses".
You can verify your storage amount under the Storage section of your account.
Use the Zotero Connector for Firefox or Chrome.
Note that you cannot transfer citations between Word and a Google Doc so it's best to insert citations only using Word or only using Google docs.
Zotero makes it easy to view the article for a citation that you have saved in your Zotero collection, but there is a setting that you can adjust to make it more reliable from off campus.