Question: I need to understand the fine details, possibilities and pricing of Salesforce OEM model. I can't find an official link about this on salesforce and google, only link available is this 2008 pdf : <http://www.developerforce.com/tdf/2008/april/Force_ISV_Partner.pdf>

Please share any good post/article on this.

Answer: 
I recently wrote a blog post about [locking records using approval processes](http://verticalcode.wordpress.com/2012/07/26/locking-a-record-from-editing/). It is a pretty big hack, but it allows you to lock a record without having to use separate page layouts or record types. Here's how it could work:

1. Set a time-based workflow rule to update a boolean field called "Lock Record" 90 days after the Opportunity is closed.
2. Have a trigger that fires when the "Lock Record" field is checked.
3. The trigger invokes a simple approval process that when finished leaves the record locked.

Admins can unlock the record by clicking the Unlock button at the top of the page, but they can also edit the record without unlocking it.
The best non-record type solution I can think of is to have a time-based workflow change the owner. You could then use sharing rules to give other users read-only access to the records.

In addition, while extra record types might be cumbersome to maintain they still might prove to be the simplest and cleanest solution in the end.