MSDN subscriptions are licensed per-user, and some subscriptions do include perpetual rights to the software and keys obtained while they were active. Subscriptions can be sold or transferred to a third party, and when this is done, the perpetual rights
also transfer to the person. This is covered here. Subscriptions are not licensed per computer or per business.
When you say that you had one license, then one person at your company is licensed to use the MSDN software and keys that was obtained while it was active. If that person leaves the company, the license can be transfered to another person, but all
keys and all software that the departing person used need to be uninstalled and transferred to the new person.
I hope this helps. Let me know what other questions you have.
MSDN and TechNet Subscriptions Support
Read the Subscriptions Blog!