I'd tackle this from a data model point of view
A assets has a name an expected life (in months), renewal dates, licences and a type which you can store in one table and then link to facts about.
These facts include different types of costs estimated and actual, ownership, location etc...
Initial purchase cost and monthly running costs (note this could be fixed or variable over the life of the asset). I would build up these datasets either in the source data, excel,sql etc. by month. this would allow you to plot variable costs and give you a more flexible and accurate forecast model.
Finally for asset management its important to note any asset dependencies which you can do by adding a parent asset key to your model so you can identify what the total impact of an assets failure, renewal might be.