Versión 7.9.17
Sugar Versión 6.5.25
It is possible to disable (read-only) certain fields of the opportunity editing form, based on the status of the opportunity and also based on this disable fields in forms of other modules.
I haven’t done anything like that but here are some posts that should give you an idea on how to achieve it:
https://community.sugarcrm.com/thread/19671#69914
https://suitecrm.com/suitecrm/forum/suitecrm-7-0-discussion/11050-display-subpanel-based-on-field
https://suitecrm.com/suitecrm/forum/developer-help/19119-field-level-access-control
https://suitecrm.com/suitecrm/forum/suitecrm-7-0-discussion/21140-create-dynamic-field?start=30